Nightwing

Dick Grayson  is the first hero to wear the mantle of  Robin. He would outgrow this and be inspired by Superman  to become the vigilante  Nightwing

Early Life
Richard John "Dick" Grayson was the youngest of The Flying Graysons, a family circus act. One night, on tour to Gotham City, the Haley Circus (where Dick performed) was sabotaged by crime lord "Boss" Tony Zucco, and Dick watched in horror as his parents' high wire snapped, sending them to their deaths.

Robin
After this, he was adopted by billionaire Bruce Wayne  and soon learned his secret; he had an alter ego as Gotham's vigilante protector Batman. Bruce trained Dick, and he would soon become Robin, Batman's sidekick, or as he preferred, partner.

Nightwing
After years of fighting crime with Batman, Dick outgrew the role, and after an argument with Bruce, approached Superman for guidance. Superman told him of the Kryptonian hero, Nightwing, who in turn was named after a Kryptonian god. Dick was inspired by this, and took the name of Nightwing himself, setting out alone against crime.