An omnivore is a creature that (when tamed) will eat most comestibles; they will readily eat anything that is suitable food for carnivores or herbivores. This includes corpses that are not rotten, meat items, fruits, vegetables, plants... pretty much anything except for tins. They will tend to eat eggs and corpses that they find on the ground. Many humanoid monsters are omnivorous.
Note that some pets will eat anything if sufficiently hungry - a good example is a dog, which will NOT eat a cram ration in the dungeon, unless very hungry, at which point it will happily eat it. Dogs are not considered omnivorous.
List of omnivores:
- chickatrices, cockatrices, and pyrolisks
- mind flayers
- vampire bats
- nagas and hatchlings that are not black
- green slime, gray oozes, and puddings (will also eat tainted corpses)
- quantum mechanics
- monkeys, plain apes and sasquatches (bananas are treats)
- humans that are not monks
- gelatinous cubes are a special kind of omnivore that can eat anything organic (including leather, cloth, paper and wax)