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This is a list of most specifically known Yeerks. Yeerk numbers are pronounced one at a time; for example, Aftran 942 would be said "Aftran nine-four-two." Yeerks with zeros in their designation can be pronounced as "zero" or "naught", as in Carger 7901: "Seven-nine-zero-one" or "Seven-nine-naught-one".

Aftran 942[]

Aftran 942 is a Yeerk, but unlike the majority of her species, she does not want to dominate other species. Her host was a young girl named Karen. When Cassie ran away from the Animorphs in The Departure (#19), she met a lost Aftran but didn't kill her because she didn't want to kill Karen.

Aftran tried to explain the Yeerks' plight to Cassie, who wound up making a deal with the alien. If Cassie would become a nothlit, stuck permanently in the body of a caterpillar, essentially taking upon herself the 'punishment' that she would be condemning Aftran to if Aftran left her host, Aftran would free Karen and would no longer infest any other human. Cassie agreed. Near the end of the two-hour morphing limit (the point of no return as far as morph went), Aftran told Cassie she could return to human form, but the caterpillar had no sense of hearing. She later was able to morph back, as caterpillars "naturally morphed" into a butterfly, which reset the morphing clock.

It is later revealed in book #29 The Sickness that Aftran has become the leader of the Yeerk Peace Movement, Yeerks who do not wish to dominate their hosts. When Visser Three found out about this movement, Aftran was captured. Mr. Tidwell, one of the teachers at the Animorphs' school and one of Aftran's allies, tells the Animorphs. Because the other four Animorphs and Ax were disabled by an Andalite flu, Cassie went in there with Mr. Tidwell and managed to rescue her. Aftran later helps Cassie operate on Ax to remove a gland in his brain that would have killed him, entering Ax as a host and subsequently 'guiding' Cassie to the appropriate part of Ax's brain to allow her to remove it. Knowing that she was going to starve to death, Aftran asked Cassie to kill her; however, Cassie and the others agreed to give her the morphing power to become a nothlit. She chose to become a male humpback whale.

Akdor 1154[]

Akdor 1154 led the uprising against the Andalites. Akdor understood the concept of using a host body to act as a predator, and he personally killed four Andalites. Died on the campaign for the Hork-Bajir.

Alahar 7865[]

Alahar 7865 appeared only in The Hork-Bajir Chronicles. He was the Yeerk that piloted Esplin 9466's Bug Fighter, and he was often panicked.


Arklan had a Gedd host and was severely wounded by Shredder backfire during the Hork-Bajir Campaign.

Carger 7901[]

One of Visser Three's peers during the battle for the Hork-Bajir world who appeared in The Hork-Bajir Chronicles. He started referring to himself as "sub-visser" and gave the order to have Seerow and his family incinerated, over Esplin (Visser Three)'s protests to wait for the fourth Andalite, Aldrea, to appear. Esplin's advice was not heeded, but later proven the wiser, when Aldrea later became a leader of the Hork-Bajir resistance to the Yeerk invasion. Esplin considered him too aggressive and crude. Carger is killed when a Jubba-Jubba bites off his host's head.

Council of Thirteen[]

The Council of Thirteen is the top governing position of the Yeerk Empire, above all the Vissers in rank. The Council is rarely seen, but mentioned fairly often; Visser Three often discusses his dream of becoming a Councilor, as do Visser One and likely all the most prominent Yeerks. Their only appearance in the series is in VISSER, chronicling Visser One's trial before the Council. Though she escaped their wrath on that occasion, it was short-lived, as they ordered her executed when she failed them on the Anati world.

The Council apparently existed before the Yeerk Empire; Visser Three mentions it had already been in place during the time of The Hork-Bajir Chronicles. One of the thirteen is Emperor, though only the Council knows who; the Emperor's identity is kept secret, so that no assassin, Yeerk or otherwise, could succeed in killing him without killing the entire Council. Also unknown is the Council's location (their Visser appearance was via hologram) or their ultimate fate, after more than half of their forces were defeated in the final battle for Earth.

Only one Councilor, Garoff 168 (see below), is identified by name. He, along with most of the Councilors, have Hork-Bajir hosts, while two have Taxxons. Two Councilors remain forever concealed in the shadows, making their forms unknown. They all wear dark red (almost black) robes.

Derane 344[]

A Yeerk that Eslin 359 had affectionate feelings for, with an unknown human host (likely female, as Eslin's host was Gary Kozlar, a male). She was killed by Visser Three (indirectly through denial of Kandrona due to shortage and low rank), and it is because of this that Eslin strikes a truce (albeit temporary) with Aximili in book #8 The Alien. Eslin explains to Ax that he and Derane came from the same pool, went through training together, and were very close.

Eslin 359[]

Ax meets Eslin 359 in The Alien (#8), three weeks after the Animorphs destroyed the Kandrona machine in the previous book. The Yeerks had to keep going up to the mothership (the Pool Ship) to receive a minimal amount of Kandrona to survive. However, there were too many Yeerks and not enough capacity, so many Yeerks died. Eslin lost his lover (Derane 344) and was angry, sabotaging a feeding schedule as revenge. When he meets Ax, he gives him the location of Visser Three's next feeding ground in the hopes that Ax would exact vengeance. However, although Ax poisoned Visser Three, the Yeerk itself (Esplin 9466) slipped out and Ax could not bring himself to kill a fellow Andalite warrior (Alloran). Eslin sneered at this failed attempt but did not report Ax to his superiors. Ax met him one last time to relay a message to the Andalite home world. His human host's name is Gary Kozlar.

Esplin 9466 Lesser[]

Esplin 9466 Lesser is a Yeerk who appears in book #16 The Warning. The double six at the end of his name signifies that he was formed from the same grub as another Yeerk, half of a pair of twins. However, his identical brother happens to be the same Yeerk who is Visser Three. In the case of twins, the one designated as the greater gets more power and rewards. However, as Visser Three is a power hungry Yeerk, he decided to snatch all the power and rewards, allowing Esplin 9466 Lesser to only have whatever he could salvage.

However, Esplin 9466 Lesser turns his misfortune around. His host is Joe Bob Fenestre, and Esplin invented Web Access America (an analogue of America Online, the world's most popular Internet service provider) through his host, which was an easy task for superior Yeerk technology. It made Fenestre a billionaire. Joe Bob's Horatio Alger story, as he progressed from an ordinary telephone repairman to an Internet pioneer, has become famous enough by the time of the Animorphs story that Marco regards him as a hero.

He obtains vast knowledge of information by sifting e-mails and spying chat rooms. He was a great asset for the invasion. Visser Three, fearing his rising popularity and ambition, declared him a traitor, which forced Esplin 9466 Lesser into hiding. Esplin uses Fenestre to build a huge mansion and heavily guard it. Knowing that his twin's host has the ability to morph into animals of all sorts, he equipped his mansion with weapons, ranging from Rottweliers and guards with submachine guns to insecticides and bug zappers to electrical force fields. His guards have instructions to shoot anything that attempts to come close to the house. This poses a great difficulty to the Animorphs; when they attempt to pay him a visit, Rachel and Ax are captured and they are forced to retreat, although Jake subsequently breaks through the defenses by acquiring a rhinoceros morph.

He explains to the Animorphs that the only reason why he is still alive today is due to his technique of survival. Cut off from Kandrona rays, he is now a cannibal. He captures fellow Controllers, splits the human host's head open, and grinds the Yeerk body inside into a powder that he then ingests. Visser Three keeps him alive only because he wants to learn that technique; but, as he explains, the technique would never catch on very well for the rest of the Yeerks.

After explaining this to the Animorphs, Cassie, horrified by his cold-blooded attitude towards humans and Yeerks, demands that Jake kills Esplin. Jake, however, had already agreed not to harm him, but adds a condition: Esplin may never leave his mansion again, or the Animorphs will find him and kill him. Esplin agrees. However, by the end of the book, his house burns down under mysterious circumstances; it is implied, but never stated, that Jake or Cassie may have done this. Nobody died in the fire, but Esplin's fate afterwards is never disclosed, including whether or not Jake fulfilled his pledge to kill him or if Visser Three thought that his brother's habits were killing too many Yeerks and destroyed his brother once and for all.

Esplin 9466 Lesser makes a minor appearance in the prequel, The Hork-Bajir Chronicles, which chronicles the origin of Visser Three, appearing alongside his twin before the Yeerks are attacked by Aldrea's army of Hork-Bajir and Arn-created monsters. He and his twin are joking together on the edge of a Yeerk-felled Nawin Speaking Tree which had been cut into to make a Yeerk pool.

Essak 241275[]

The Yeerk supposedly in Jake's head in the alternate future he visited in book #41 The Familiar. He was a planetary engineer working on the project to convert Earth's moon into a Kandrona-radiating miniature sun, based in the Chrysler Building.

Essam 293[]

Essam 293 is a Yeerk engineer based on the Yeerk home world who appears in Visser in the form of flashbacks. He accompanies Edriss 562 (then Sub-Visser 409) on her mission to find Earth, and later falls in love with her. He infested a human named Hildy Gervais. In human hosts, they conceived twin children, Darwin and Madra. However, he later disagreed with Edriss' philiosophy and tried to defy her; Edriss cut off Kandrona rays. Essam died of Kandrona starvation.

Estril 731[]

Estril 731 is the brother of Aftran 942. Before his death, he was the controller of a Hork-Bajir. In book #19 The Departure, Jake gives the order to call off their attack immediately before Cassie rips out the throat of Estril's host. This guilt pressures her to temporarily leave the Animorphs.

Garoff 168[]

Garoff 168 is a member of the Council of Thirteen and Edriss 562's former mentor, whose sole appearance is in VISSER. He is the speaker at the trial of Edriss 562. During the trial, Edriss strongly suspects that he is the Emperor, and wonders if only his opinion matters. Garoff is sympathetic to Edriss and tries as much as possible to get her free. For instance, when it is clear that Edriss has committed treasonous acitivities, he decides to resume the testimony instead of convicting her. Edriss is stunned at first, but it is her host, Eva, that realizes that Garoff is trying to get her free. Garoff controls a Hork-Bajir host.


Illim is the Yeerk who controls Mr. Tidwell, a teacher at the Animorphs' school. He appears in The Sickness (#29). He is a member of the Yeerk Peace Movement, having come to sympathize with his host after experiencing his screams of torment (although the two have since become friends) and a friend of Aftran 942. Cassie acquired Illim as a morph in order to infiltrate the Yeerk pool and rescue Aftran.

Iniss 455[]

A Yeerk that Visser Three had reserved for Melissa Chapman, but she was not present at the time. Mentioned (but not seen) in book #2 The Visitor.

Iniss 226[]

The Yeerk in control of Hedrick Chapman, a high ranking Controller. Iniss 226 agreed to cooperate with his host, Hedrick Chapman, who desired above all else to protect his daughter Melissa; he briefly incurred Visser Three's wrath over this. His exact rank is unknown, but he seems to be below Sub-Visser Fifty-One.

Iniss 174[]

Mentioned in book #2 The Visitor, Iniss 226 tells Mrs. Chapman's Yeerk how Visser Three showed him a hologram video of how he morphed a Vanarx and sucked Iniss 174 out of a woman's head and ate the Yeerk.

The Inspector[]

The Inspector was sent to check up on Visser Three's progress on the invasion of Earth. His host is a Garatron, an alien similar to an Andalite, but one that moves much faster. However, he is bitten by Marco in cobra morph. Visser Three decides not to help him, because he knows the Inspector would have given him a bad review. The Inspector dies from the poison.

Janath 429[]

A very old Yeerk and apparently one of some level of importance. He was present during the declaration of the Yeerk Empire and its plans to conquer the Hork-Bajir homeworld. Died during the Yeerk conquest of the Hork-Bajir.

Jillay 926[]

A Yeerk from book #14 The Unknown who was part of the mission to enter Zone 91 controlling a horse to find out what non-human thing was being hidden there. He was killed when he could not tell Visser Three what they had seen inside the base.

Kilgam 329[]

A Yeerk with a Gedd host, seen in chapter 2 of VISSER. He speaks up during Sub-Visser 409's lecture, and its host is killed by Edriss immediately after giving its name. Kilgam manages to crawl out of the Gedd's ear before the death completely reaches it. He is then taken to the pool.

Korin 547[]

A Yeerk from book #14 The Unknown who was part of the mission to enter Zone 91 controlling a horse to find out what non-human thing was being hidden there. Called a "clumsy fool" by Visser Three, he dies when he is bitten by a snake.

Lacsar 454[]

One of the Yeerks on duty as a security guard at the new community center in book #33 The Illusion. He is mentioned by one of the security guards wearing boots, saying he "just left the entrance" and passed his shift off to Lascar 454.

Methit 572[]

Methit 572 appears in chapter two of VISSER, delivering news (from the Taxxon homeworld) to Sub-Visser 409 of a Class Five species. The report claims that humans may exist in billions. These humans are in fact Loren and Hedrick, in a scene that takes place in The Andalite Chronicles.


In Book 41: The Familiar (narrated by Jake) Niss is the Yeerk who controls future Cassie. She is part of the Evolutionist Front (The EF), a group of Yeerks who wished to create artificial symbiotes rather than taking natural, sentient hosts.

Odret 177[]

Odret 177 is the Yeerk who infests Tobias in Megamorphs #4: Back to Before. The book is set in an alternate universe that chronicles what would happen had the Animorphs not received their powers. Tobias joins the Sharing and becomes a Controller. He almost willingly surrenders his freedom, but resists at the last minute. Odret is loyal to the current Visser One, Edriss 562, which leads to his execution by Visser Three.

Sub-Visser 19[]

Sub-Visser Nineteen is Aftran's commander, mentioned in The Departure.

Sub-Visser 51[]

Sub-Visser Fifty-one is the Yeerk controlling the human Taylor. Sub-Visser 51 previously only had infested a Hork-Bajir. Taylor is its/her second host, and first human host. More information on the relationship between Sub-Visser 51 and Taylor can be found here.

Sub-Visser 74[]

Sub-Visser Seventy-four appears in book #54 The Beginning. She controls a Hork-Bajir female, and serves as the spokesperson for the Yeerk prisoners of war when speaking to Jake after the capture of Visser One.

Sub-Visser 92[]

In chapter 24 of VISSER, Edriss 562 describes to the Council of Thirteen how she reported to Sub-Visser Ninety-two that she had found a Class-Five species, in the early 1990s. Sub-Visser 92 is surprised that there are five billion, rather than million, Class-Five humans on Earth, so much so that he cuts himself with his own Hork-Bajir blades by sitting up too quickly.

Temrash 114[]

Temrash 114 (formerly Temrash 252 of the Sulp Niar pool, later promoted) is a Yeerk who infests both Jake (in #6: The Capture) and his older brother Tom previously. Temrash was originally waiting for a promotion (to infest the Governor) when the Animorphs invade the Yeerk pool (a smaller one contained in a spa inside a hospital room). After being shot, Jake falls in, and Temrash infests him to avoid death when one of the Animorphs boils the Yeerk Pool (by turning on the spa's jets and heater). He first believed that he could fool the other Animorphs, but they soon realize that Jake is not acting normally when Temrash instinctively sneers at Ax and then calls him "Andalite filth" when Ax is acquiring him. Determined to eliminate the Yeerk, the Animorphs tie Jake up in a cabin in the woods for three days until Temrash dies; although he attempts to escape on multiple occasions, the others are always able to recapture him. His death causes Jake to see Crayak, a recurring dream that haunts him until book 26, when the Animorphs confront Crayak on the city of wonders (the Iskoort home world).

Tom's second Yeerk[]

After Temrash 114, Tom Berenson received a second Yeerk, but this Yeerk is never named. By the end of the series, it is likely that Tom's second Yeerk was promoted to at least Sub-Visser status. In the TV series, the name of this Yeerk is Iniss 335.

Visser One[]

Visser One is a rank in the Yeerk military, where "Visser" is analogous to General. This title is held by at least two Yeerks during the course of the Animorphs series: Edriss 562 and later (after the death of Edriss) Esplin 9466 Primary.

Visser Two[]

Visser Two is the Yeerk controlling a human who orchestrates an attempt to start a World War III in book #46 The Deception (#46). His host is an officer of the aircraft carrier USS George Washington. When something attacks the George Washington, he arranges for a fake report to state that it was from a Chinese submarine. According to his plan, several hours later, the U.S. government will receive a report that the Chinese made an unprovoked attack, which would lead to World War III, with millions of lost lives. Only Visser Two had the authority to stop his men from shooting, so Ax morphs into his host and other various humans. Ax hijacks an F-14 Tomcat with a nuclear weapon and puts Visser Two in the cockpit with him. Ax calmly states that he will bomb the location of the Yeerk pool (having a single bomb that was loaded previously on the plane), killing thousands of Yeerks, in an attempt to convince Visser Two to call off the attack. Furious, Visser Two agrees, and his plan is defeated.

Visser Three[]

Visser Three is a rank in the Yeerk military. For the majority of the series, this rank is held by the Yeerk known as Esplin 9466 Primary.

Visser Four[]

Visser Four is the Yeerk who infested John Berryman who appears in Elfangor's Secret (Megamorphs #3). He lost the rank of Visser Four after losing the campaign on Leera to the Animorphs (book #18 The Decision). In Elfangor's Secret (Megamorphs #3), he discovered the Time Matrix and intended to use it to change history, in order to make the future invasion easier for the Yeerks. When Crayak and the Ellimist deemed him dangerous, they sent the Animorphs after him. They managed to finally stop him on D-Day on the beaches of Normandy. In the ensuing chaos, Marco throws him into a burning tank. With the Time Matrix, the Animorphs rewrote the past so that Berryman would never exist, and Visser Four would presumably have never infested him.

Yaheen 747[]

Known to Aftran 942, Yaheen 747 is a Controller with a state policeman for a host. He is a member of the search party looking for Karen and Aftran in the woods in book #19 The Departure.