Day Twenty-Nine: Your favourite alien species.
Did you read 1984 by George Orwell? There's this part of the book where the protagonists, all along thinking that they were alone in the room, said "We are the dead". But then someone responded, "You are the dead". That scene, while reading it, was the most chilling but/most terrific thing that I've read.
I associate that feeling to Howlers, too.
Howlers, the alien species made by the evil Crayak, are made to play a game - killing game. They are these babies that thought the poor thing that they're killing is a toy that they must play with.
I applaud K.A. Applegate for creating them. What they're doing was sick, but they're innocent; they don't know that killing is a vile thing to do, so you don't know how/what to feel for them.
I love Animorphs for all the mindfucks it gave me, and the Howlers definitely did this to me too, that's why they're my favorite aliens.