Crocodiles are reptilian creatures that can be found in the real world. We see our first crocodiles make a brief appearance in the episode "Video Makers." Finn instructs Slime Princess to swing from a vine over the crocodiles and land safely. Instead, she lands in the water, and the crocodiles dive in after her. One of the crocodiles emerges from the water with Slime Princess kissing its snout.
We again see a pair of crocodiles in Peppermint Butler's lair. It is unknown wether or not they are alive, as they are seen laying very still.
Like many of the minor animal characters, the crocodiles sport a very traditional look: dark green, with long snouts and tails, and sharp teeth.