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.
Dick Grayson
After spending some time away with Bruce and Tim to heal and rebuild after their harsh times prior to the Crisis, Dick relocates to New York, but has trouble finding work as both Dick Grayson and Nightwing. During the "Batman R.I.P." storyline, Nightwing is ambushed by the International Club of Villains. He is later seen being held in Arkham Asylum, where one of the surgeons, in reality also the civilian identity of ICoV member Le Bossu, arranged for Nightwing to be admitted under the name of Pierrot Lunaire (another ICoV member) and be kept both heavily drugged and regularly beaten by staff to subdue him. Scheduled for an experimental lobotomy by Le Bossu himself, he manages to free himself and come to Batman's aid for the finale of the story arc.