Nightwing is a superhero appearing in American comic books published by DC Comics. The character has appeared in various incarnations; the identity is adopted by Dick Grayson when he leaves 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 was an identity assumed by Superman when stranded on the Kryptonian city of Kandor with 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. Other stories set among the Batman family of characters have seen acquaintances and friends of Grayson briefly assume the title, including his fellow Robin alumnus Jason Todd. Meanwhile, Superman stories have seen Superman's adopted son Chris 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. In 2013, Nightwing placed 5th on IGN's Top 25 Heroes of DC Comics and Grayson as Nightwing was ranked the #1 Sexiest Male Character in Comics by ComicsAlliance in 2013. Fictional character biography Pre-Crisis Era Superman Nightwing is first depicted in the story "Superman in Kandor" in Superman #158 (January 1963). It is an alias used by Superman in pre-Crisis stories. The story is set in Kandor, a Kryptonian city that was shrunken and preserved in a bottle by Brainiac. In Kandor, Superman has no superpowers, and is branded an outlaw there due to a misunderstanding. To disguise themselves, Superman and Jimmy Olsen create vigilante identities inspired by Batman and Robin. Because neither bats nor robins lived on Krypton, Superman chooses the names of two birds owned by his Kandorian friend Nor-Kan: Nightwing for himself, and Flamebird for Jimmy. Nightwing and Flamebird rename Nor-Kan's underground laboratory as the "Nightcave", and use it as their secret headquarters. They also convert Nor-Kan's automobile into their "Nightmobile", and use "jet-belts" to fly into battle. In Superman's Pal, Jimmy Olsen #69 (June 1963), "The Dynamic Duo of Kandor" introduces Nightwing's dog Nighthound. In "The Feud Between Batman and Superman" in World's Finest #143 (August 1964), Batman and Robin themselves visit Kandor with Superman and Olsen