Nightwing is a superhero identity assumed by numerous fictional characters in the DC Comics universe. Most prominently, Nightwing is the superhero name adopted by Batman's partner Dick Grayson when he outgrows his identity as Batman's sidekick Robin. Nightwing remains strongly associated with Batman, but the title and concept have origins in classic Superman stories.
The original Nightwing in DC continuity was an identity assumed by alien superhero Superman when stranded on the Kryptonian city of Kandor with his friend Jimmy Olsen. Drawing inspiration from Batman and Robin, the two protect Kandor as the superheroes Nightwing and Flamebird. Following a continuity reboot in 1985, Nightwing is a legendary figure much like Batman from Krypton, and it is this legend which inspires Dick Grayson's choice of name when he sheds the name Robin.
Other stories set among the Batman family of characters have seen acquaintances and friends of Dick Grayson briefly assume the title, including his fellow Robin alumnus Jason Todd. Meanwhile, Superman stories have seen Superman's niece Power Girl and adopted son Chris Kent take up the name for brief turns as Nightwing. Various other characters have taken the name in stories set outside DC's main continuity as well, and at times the role has been unoccupied, such as when Dick Grayson operated as Batman and after faking his death.