Katie Holmes isn't the first actress you think about when you think action movie. She's kept her 'Dawson's Creek' homely appeal ever since being on the show in her teens. There is one quality she has that is perfect for Wonder Woman though, and that's her warmth and kindness. She exudes warmth, which makes me able to picture her as Wonder Woman, even if she isn't as athletic as Gal Gadot. Sometimes it is hard for an actor to break out of a long-running television role.
Katie Holmes made an odd comment to Sirius XM radio in 2014 when she said, "I wanna be Wonder Woman. I might need a tramp stamp." I think she may have been addressing her homely quality, but your guess is as good as mine as far as what that comment means.