Um...Dr. Doom. All Dr. Doom. Don't get me wrong, it's totally a MotU thing, but I set this up before the MotUC collection began getting as big as it is now, and I don't really wana take it down. I put up both my classic and 200X Greyskulls side by side, and set up all my various Dr. Doom figures around and on them because Doom usually has a castle and - hey - they're green! It matches! And I wanted a setup for my Doom collection.
So yeah, there you go. Dr. Doom has stolen all the secrets that the castle holds, and multiplied himself within.