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.
Batman (Terry McGinnis)
Though Terry never met Batman's former sidekick that was Robin and Nightwing in the animated series, the two did get the chance to meet in the tie-in comic. They work together to bring down Hush (who was a failed clone of Grayson), and Dick helped Terry with handling the Jokerz bombing Gotham and Undercloud. Though Dick was uninvolved in the superhero community for quite some time after losing his eye during a fight between Batman and the Joker, Terry has inspired him to return to the spotlight. When a GCPD detective outs Dick as Nightwing to the public, Terry and Max try to make the public think otherwise by having Terry interrogate the detective as a disguised, older Nightwing while Max plants alibis on the internet. Dick admits the truth to the public without jeopardizing his allies' secrets.