Visser Three
 
Esplin 9466, Visser Three, or later, Visser One is the main villain in the Animorphs series. A ruthless Yeerk, he was the first of his kind to infest an Andalite host body. With the body, he was able to tap into Andalite technology, for example taking on different forms. Esplin had a twin brother named Esplin 9466 Lesser, whose fate is unknown. In the series he tried to cause an invasion on Earth. He is also the nemesis of the Animorphs. He was also known for making up excuses to execute people. In book #45, he was appointed to Viseer One after the failure of the original. At the end, he accepts his defeat saying that "Any punishment that you inflict, would be nothing compared to what the Council of Thirteen would do." His ultimate fate was being incarcerated in prison deprived of sight, and without a host body. He also appeared in the television series.