Kronosaurus ("lizard of Kronos" or "time lizard") is a genus of pliosaurid plesiosaur that lived during the Early Cretaceous period in Australia. Its name comes from the Titan Kronos in Greek and Roman Mythology, who controlled time. It was a carnivorous marine reptile, eating fish, plesiosaurs, and even smaller Kronosaurus. It was the largest known carnivore in Australia's seas at the time, making it the top predator in its domain. It was a close relative of Liopleurodon.

In The Land Before Time

A pair of Kronosaurus briefly appear in The Land Before Time (TV series) in the episode "The Missing Fast-Water Adventure", where they are seen during the episode's reprise of the song Big Water. They are most likely only seen in a fantasy.