3. Tyler Hoechlin
Tyler Hoechlin was one of the names on the shortlist to play Bruce Wayne in BVS, but Snyder ultimately turned him down because they were looking for a much older Caped Crusader. The 26 year-old may not have been the right fit for that part, but is definitely right for the role of Dick Grayson. He first came onto the scene as Tom Hank's son in Road to Perdition, then landed the role of Martin Brewer in 7th Heaven, which he played from 2003 to 2007. He did a few film gigs after that but is probably best known for his current role of Derek Hale on MTV's hit show, Teen Wolf. His role as a werewolf week to week shows he's got the size and build for Nightwing, and has the rough, handsome looks required for the part. He also stands as a good counterpoint to Affleck, which could prove beneficial when playing a former sidekick who seems to be on the outs with his old mentor.