Plain and simple here. It doesn't have to be 1, it can be multiple-or have a top # list. Reason behind your choice is optional.
I'll go first
One of my favorite aliens are the Unggoy (better known as Grunts) from HALO. Personally I think they're the most humorous in terms of voices, dialogue, and how they act. I feel bad for these guys because of their backstory in the lore, however I facepalmed at the time I saw their Halo 4 appearance...They look like midget Krogans from Mass Effect...Because of their face
Updated by Lekkiyo