Nightwing

Nightwing is a fictional character and superhero appearing in American comic books published by DC Comics.  The character has appeared in various incarnations; the identity was adopted when he left his role as Batman's vigilante partner Robin. 

Although Nightwing is commonly associated with Batman, the title and concept have origins in classic Superman stories. The original Nightwing in DC Comics 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. Nightwing was re-imagined as a legendary vigilante from Krypton whose story inspires Dick Grayson's choice of name when he leaves behind his Robin identity. 

Other stories set among the Batman family of characters have seen acquaintances briefly assume the title, including his fellow Robin. Meanwhile, Superman stories have seen Superman's adopted son Christ Kent and Power Girl 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.