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"We are the Yeerk Empire! We are not a race of sneaks and spies. We are rulers, conquerors!"
Esplin 9466[src]

The Yeerk Empire was a Yeerk colonial empire founded by Akdor 1154. Wishing to conquer all sentient races in all galaxies, the Empire was officially established in 1968 after Akdor arrived on Sector 5, RG-21578-4 and learned they could use the Hork-Bajir as shock troops. For three decades, the Empire fought against the Andalites throughout space.

Edriss 562's confirmation of humans being viable hosts led to the Yeerk Empire launching a secret invasion of Earth in 1995, beginning their operations in California. In 1997, Esplin 9466 was placed in charge of the Earth invasion, although for three years his efforts were impeded by the Animorphs. In 2000, the Empire began open warfare on Earth. Shortly after, the Animorphs' capture of the Pool ship resulted in official Yeerk surrender, ending the Andalite-Yeerk War and dissolving the Empire.

As per the terms of the surrender, all remaining Yeerks, with the exception of Esplin 9466, were to be granted the morphing ability on the condition that they trapped themselves in morph. However, a small number of Yeerk forces who were not on Earth refused to comply to these terms, and by 2003 were still being hunted by Andalite forces.


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"I was there. Do you understand what this moment was, what it meant? I was there when Akdor announced the birth of the Yeerk Empire."
Esplin 9466[src]

In 1968, after landing on the Hork-Bajir homeworld, Akdor 1154 had three Hork-Bajir captured, with one being infested by Esplin 9466. After Esplin confirmed that the numerous Hork-Bajir hosts could be used as shock troops and weapons to fight the Andalites, Akdor created the Yeerk Empire and began mass infestation of the species.

In 1997,[2]


"There was talk of creating new ranks. Everyone said that if we were going to become a conquering army, we would need a hierarchy. The ancient Council of Thirteen would remain all-important. But beneath that would come something called "vissers" and "sub-vissers.""
Esplin 9466[src]

Council of Thirteen[]

The Council of Thirteen is at the top of the Yeerk hierarchy. One of the members of the Council is the Emperor, but only the Council members know which one. There are a variety of hosts on the Council including Hork-Bajir and Taxxons. There are no humans on the Council, and no Andalites as Visser Three/One was never appointed to the Council.


Just below the Council of Thirteen are the Vissers, generals of the Yeerk empire. The lower the number the higher ranking the Yeerk, therefore Visser One is the highest, and this goes on down until Visser forty-seven or so.


Below Vissers are Sub-Vissers. They are the colonels of the Yeerk empire, having subordinates but still taking orders from a superior officer. The same applies to Sub-Vissers as Vissers, the lower the number the higher the ranking. There are about 200 Sub-Vissers according to The Andalite Chronicles. In VISSER it is revealed that there are over 400.


  1. According to #54: The Beginning, it is in California. VISSER also reveals it is mid-sized coastal city, with series co-author Michael Grant describing the fictional city as a blend between Orange County and Long Beach.
  2. The Andalite Chronicles takes place in 1976 and states it is 21 years before Elfangor met the Animorphs, placing the event in 1997.