Earclopses

Earclops are large, giant creatures with ears for heads from "The Silent King". They are the army of Xergiok. Finn and Jake combined defeated them by making a very loud sound.

Trivia

 * They are most likely based on Cyclopes, the mythical giants from Greek mythology with one eye in the middle of their foreheads.
 * Apparently, you shouldn't use an Earclops to battle unless you bring earplugs.