You missed Solomon Grundy, but he may fall into "DC" than "Batman".
Mr. Freeze would be pretty good as a star. Make him a scientist who desperately turns his research into a weapon, possibly to get funding, gets mocked for it, gets it to work, starts using it for crimes as his funds run low, desperately experiments on himself, all the while he knows Batman is on his trail.
Hush would be tough to have a movie, since his part of his whole thing is his identity being a mystery.
Red Hood Could work. His ID only needs to be a mystery to Batman, so once it's out it's fine.