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.
Nightwing
Following the events of Batman's apparent death during "Final Crisis", Nightwing has closed down shop in New York so as to return to Gotham. He has opted to give up on having a normal job, and instead intends to put all his effort into protecting the city. After his returns he confronts Two-Face and Ra's al Ghul, proving two of his mentor's greatest enemies that he is an equal to Batman after he defeated them. He also finds himself being tasked to raise Bruce's biological son Damian with Alfred.