For the last couple weeks, there's been a rumor going around that Dick Grayson as Nightwing will be in the Batman Vs. Superman movie. In fact, Girls star Adam Driver was reportedly even the frontrunner for the role.
However, in an interview with Collider, Adam Driver has denied the rumor. Of course, Driver is just denying the rumor that he's up for the role, so it could very well still be true that Nightwing is in Batman Vs. Superman.
It's also possible that Driver could be under orders from Warner Bros. to deny everything, but he really comes across as genuine when he says there's nothing to the rumors. However, Driver does say it's "intensely flattering" for his name to be out there as being a possibility for the role.
Batman Vs. Superman is scheduled to open in movie theaters on July 17, 2015.