Nightwing
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 pal Jimmy Olsen. Drawing inspiration from Batman and Robin, the two protect Kandor as the superheroes Nightwing and Flamebird. Following the Crisis on Infinite Earths continuity reboot in 1985, 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.
Robin (character)
The character was rediscovered by a new generation of fans during the 1980s because of the success of "The New Teen Titans", in which he left Batman's shadow entirely to assume the identity of Nightwing. He aids Batman throughout the later storyline regarding the several conflicts with Jason Todd until he makes his final return as the "Red Hood". Grayson temporarily took over as Batman (while Wayne was traveling through time), using the aid of Damian Wayne, making his newish appearance as "Robin", to defeat and imprison Todd. With Bruce Wayne's return, Grayson went back to being Nightwing.