Cronus

Cronus (who also refers to himself as Kronos) was the king of the Titans in Greek mythology, and the father of most of the Gods of Olympus.

When goes to find an explanation for the bizarre occurrences in Halls of Lost Legends, his  go looking for him and find a door marked "Cronus". Thinking he may have gone in there, the Turtles come face-to-face with the Titan, who thinks the Turtles are more of his children to consume. The Turtles fight him and wound the Titan, but he continues his assault, and it is not until Donatello appears and blinds him by stabbing him in the eye with his bo, that the Turtles are able to escape, locking the door behind them.