I think it's actually been mentioned that Superman is a Vegetarian. He doesn't need to eat and gets all his nutrients from the sun. I'm not sure who said it, but one creator a while back said it, and it may have been retconned by now.
By the way, I think it's BS that Wonder Woman is a vegetarian now. She's not a hippie or an enviromentalist. She's a warrior from an island where I got the impression that her people lived off the land. She'd have respect for the animals she eats, sure, but I don't think she'd give up the way of life she was used to on Themysrica.