Dinosaurs

Monsters that are or are related to dinosaurs, most believe that all dinosaurs went extinct many centuries ago while the sole exception of avians (birds), however in many fictional works dinosaurs are alive and well, they also frequently interact with humans despite humans having evolved centuries after the extinction of non-avian dinosaurs.

Dinosaurs are also frequently depicted as dragon-like scaly monsters and only recently have began to be depicted more accurately (due to continual advances in archeology).