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
Dick Grayson is re-established as Nightwing following DC's "Flashpoint" crossover event, after which the publisher relaunched all of its titles and made alterations to its continuity as part of an initiative called The New 52. In the new status quo, Bruce Wayne is once again the only Batman, and Dick, like the other members of the adoptive family, is a few years younger. Dick, despite being 19 is drawn a bit shorter than in his pre-relaunch frame. This is likely due to adding believability to his acrobat past. According to various interviews it is stated that Dick was adopted at 16, as opposed to 12. This is due to the DCNU's timeline existing for five years. Dick Grayson is shown in flashbacks as Robin with a revamped version of the Robin costume in "Nightwing" (vol. 3) #0 (November 2012) and "Batman and Robin Annual" (vol. 2) #2 (March 2014).
In his civilian identity he is attacked by an assassin named Saiko who insists that he is the fiercest killer in Gotham. The series "Batman Incorporated" relaunches with a second volume, continuing its story while taking into account the New 52's continuity changes; Dick is now depicted as Nightwing, and not as Batman, but the change is not addressed in the comic itself. In "Nightwing", Dick inherits the deed to the circus from a dying C. C. Haly and begins a relationship with his childhood friend acrobat Raya Vestri. Saiko tortures Haly for information on Nightwing's secret identity, and the old man dies in Dick's arms after telling him the circus holds a terrible secret. Investigating leads, he tracks down a supervillain named Feedback, who used to be a childhood friend, but does not learn anything. Following Haly's clues, he finds a mysterious Book of Names in the circus that has his name on the last page. Later the circus announces they will be doing a memorial show on the anniversary of the night Dick's parents were murdered, and Saiko attacks by detonating a massive explosion.