Arnold Schwarzenegger's Mr. Freeze

Really, this list item doesn't just belong to Arnold Schwarzenegger's Mr. Freeze. Actually, every actor in Joel Schumacher’s Batman movies can be included here, as well (what he did to poor Bane"¦).
But we’re singling out Arnie's character because of the huge discrepancy between the comic book and movie characters. He had a tragic backstory in the comics, but he was just a big pun-machine in the movie. And with Schwarzenegger playing the part, it’s odd that there’s nothing menacing about the character. And who believed Arnie as a brilliant scientist?
The plot made no sense, since it pairs Mr. Freeze with Poison Ivy in yet another misstep.
If you want to cringe, watch Arnold play Mr. Freeze in Batman and Robin. But if you want to see the character played properly, watch the animated Batman and Mr. Freeze: SubZero.
