He-Man's Cthulu monster was called Sh'Gorah. At least that's what was in the FILMation cartoon. It took out Skeletor first and then went after Castle Grayskull.I'm personally a fan of the Golden Book story with the Eye of Eternia that was really a magic portal and then tentacles came out of the eye to pull He-Man in. Still, this is a great idea. It'd be the coolest crossover movie since Freddy vs Jason (because we haven't seen Batman vs Superman yet).