Creeper

A green-ish Minecraft mob that sneaks up on you, makes the most terrifying noise of all of Minecraft (Hissing) , and blows up you, and if you're very unlucky, your build. Basically a suicide bomber.

Steve: Aww man! A creeper blew up my villager breeder!!
Alex: Again? Steve you gotta start placing torches on your builds or it'll keep happening!