A Cyclophage is a one-eyed, four-legged, bipedal creature that feeds on cyclopes.
Leela's last will specified that when she died, her body was to be fed to a Cyclophage. When the Planet Express crew crashed back to Earth after passing through a wormhole, Leela fell into a coma from which she could not be woken. Her body was later taken to a Cyclophage preserve, where a red Cyclophage nearly devoured her; she woke up in time, however, and the crew narrowly escaped the creature.
Back on Earth, the crew was attacked at Planet Express headquarters by the same Cyclophage, which had clung to the ship and returned with them. The creature was killed when it swallowed Bender, whose newly-installed doomsday battery overloaded.