Om Nom is a monster that loves candy. He is from the game Cut The Rope. If he doesn't get candy, he gets sad.
He went to Candied Island to see the candy and wants to stay there forever. He thinks that he is the only living thing that has seen it in person.
Later, when he was taken to DexLabs, Dexter couldn't keep him happy. He had to put him in a room filled with everlasting candy to keep him happy while studying him and the "secret force" within Om Nom.
Fusion Om Nom is a Super Fusion, and extremely hard to defeat.