Nightwing is DC superhero, whom has portrayed by many other superheroes including Clark Kent, Dick Grayson, Jason Todd and even Damian Wayne, with the most prominent NIghtwing being Dick Grayson, whom took on the persona after he gave up the role of Batman's sidekick Robin. In his new outfit, armed with dual Eskrima truncheons, the Nightwing protects the streets of Chicago.
Nightwing as he appeared in Batman: Arkham City!
Nightwing did appear in Batman: Arkham City as a playable DLC character for the games challenge mode, playable, as all available characters were in both the combat levels and the predator levels. It seems the character may return for Arkham Knight, according to a little slip up from Rocksteady Studios lead animator Zafer Coban when he was interviewed recently at E3 by the guys over at 4Player Network (in the video below)