From the time of the immemorial, it has been the task of The Black Racer to collect the souls of fallen gods from the battlefield. Throughout that time, the identity of the Black Racer has changed. His most recent incarnation was that of army veteran Willie Walker. Currently, Black Racer has no mortal incarnation.
Willie Walker was a war veteran, who during the Vietnam War, was injured and paralyzed. Once back in America, he was a witness to a murder done by a crook named "Sugar Man." Sugar Man was going to kill Willie, even though he couldn't say anything, but Willie's despair summoned the Black Racer, who could hear his thoughts, who saved Willie and passed his power on to him. The power of the Black Racer freed Willie from paralysis, but only when he became Black Racer. Now Willie is the Black Racer, and when it was time for him to hunt his quarry (and he knew when it was the time and who his quarry is) he could become the Black Racer, relentless and unshakable in his purpose!
Death of the New Gods
Infinity-Man killed Black Racer in the first issue of eight-part Death of the New Gods mini-series, tearing out his heart so that he would not interfere with the Source's plans. Serifan, one of the Forever People, was seen leaving the room after Willie's death.
Black Racer, however, can never truly be destroyed, and is next seen in his fifth world incarnation chasing after Barry Allen, who came back from the dead to fight against Darkseid. Barry, along with Wally West, managed to outrun the Racer, but realized he'd always be pursed by the Racer since he was technically dead. The Flashes use this to lead the Racer to Darkseid, whom the Racer then collects, ending his reign over Earth.
It is also revealed that Black Racer is the same being as Black Flash.
The Black Racer's most iconic power is his touch. With a touch he can end the life of even gods. As the bringer of death, great starts are left as husks by his passing. In addition to that tremendous power, The Black Racer also has powers to aid the hunting of his quarry. His speed such that he could effortlessly keep up with Lightray going top speed, toying with him. His agility is great enough that he could easily leap over a fiery, light-speed holocaust hurled at him by Lightray. The Black Racer is able to pass through stars unfazed. He senses when a god is near death, and is able to track them, appearing instantly at their side if necessary. His healing powers cured Willie Walker of his paralysis, and his telepathy enabled him to hear Willie's thoughts of despair. He's able to fly either in an atmosphere or space. He chases quarry without effort, never tiring, never stopping, an unshakable, relentless force.
Despite all the power of the Black Racer, he must still bow to the will of destiny, which can change his course taking him where he is needed.