While Dick Grayson is the longest-running and most-remembered superhero to hold the mantle of Nightwing in the DC Universe, he is far from the first and only character to take on the superhero persona. And spinning out of the events of 2006's Infinite Crisis, Batman's second Robin, Jason Todd, filled the role of Nightwing in a much more bloody capacity leading to a showdown between the Boy Wonders that would reverberate across the Bat-Family for years to follow before an eventual reconciliation.
After narrowly being killed by Alexander Luthor, Jr. in the climactic battle of Infinite Crisis, Dick took some time off from the superhero game to accompany Bruce Wayne and Tim Drake as they traveled the world to revisit Bruce's training and become better crimefighters. With Bludhaven destroyed by the Secret Society of Supervillains during the conflict, Dick set up his new base of operations in New York City. In the meantime, Jason had recently resurfaced as the murderous Red Hood, an antihero that openly employed lethal force against the criminal element of Gotham City.
After being gravely wounded by Batman in their last confrontation before Infinite Crisis, Jason arrived in New York before Dick, now dressed as Nightwing and still killing criminals indiscriminately in Bruce Jones and Joseph Dodd's Nightwing #118. Shortly after his own relocation, Dick learned that he had a murderous imposter on the loose in the city and quickly tracked Jason down, with the two members of the Bat-Family coming to blows. Jason felt he could effectively replace Dick as a better Nightwing that was more proactive and definitive in combatting crime just as he had felt he replaced Dick as a more hard-hitting Robin all those years ago.
The two Nightwings' vendetta would come to a premature end when a pair of supervillains kidnapped Jason, which resulted in Nightwing approaching his new love interest Cheyenne Fremont to rescue him. Owing his predecessor his life, Jason returned to his Red Hood persona -- who still openly killed his targets -- but the grudge between the two would remain for years before to a head once again following Batman's presumed death at the end of Final Crisis, which left the Dark Knight mantle glaringly vacant.
All three of the original Robins would attempt to take up the role of Batman in their own way as Two-Face launched a new crime wave throughout Gotham, taking advantage of the increased chaos left by Batman's absence. Jason's version of the Caped Crusader was a gun-toting, armored incarnation while Dick was a more traditional take on his mentor's superhero persona. Finally, Dick and Tim united to separately defeat Jason and Two-Face, while Dick assumed the mantle for Batman until Bruce's miraculous return months later. By the start of the New 52 era, Jason had mended fences with much of the Bat-Family -- though visible tension still remained -- while reining in his more homicidal tendencies.
Jason Todd attempting to take over the mantle of Nightwing marked the character at his most villainous, far from the brutal antihero he would become. In a shockingly petty move, Jason made a move on his predecessor by lethally using the Nightwing persona to further his own murderous strategies regardless of Dick Grayson's misgivings. Ultimately, Dick proved triumphant and -- after a failed bid to become Batman himself -- Jason returned to the Bat-Family with his tail between his legs to come back into the fold whenever his old allies needed him. And while Dick has taken temporary respites from being Nightwing to either fill the mantle of Batman or serve as an undercover secret agent, the original Boy Wonder's best role is still as the one, true Nightwing.