

Showa Ghidorah, Final Wars Gigan or Showa Mechagodzilla. It would have to be one of these 3, but I just can't decide on who I prefer.
Long live the king...

SpaceGodzilla is my Personal favorite:)
King and Queen of The Skies.........

Kenji Sahara as Jiro Torahata. He shoots, and kills, a man in the back. Just for money. He also conspired to commit human trafficking.
Host of the podcast Giant Monster Messages where we watch EVERY giant monster film and look for the messages.

The Leader of Planet X. (Monster Zero, not Final Wars.)

King Ghidorah. I'm a fan of his portrayals in the Showa and Heisei era but not his Millennium version. The Ghidorah in GMK was too small and he wasn't evil. I do expect great things from Legendary. They seem to be going in the right direction in him.
\"SKREEONGK!\" -Godzilla

King Ghidorah as a whole.
Not because of any specific role he's had, but because he is THE arch-nemesis of Godzilla, frequently depicted as a powerhouse that Godzilla struggles against.
The perfect modern hydra that became an idol on his own. When you think of Godzilla monsters, one would be hard-pressed to not include the golden emperor, the king of destruction, the 3-headed monster himself!
There's a reason he's one of THE biggest names after Godzilla himself attached to the franchise as a whole.