Terry McGinnis was your average Gotham City teenager, who was the son of a Wayne-Powers research scientist. In his younger days, Terry was a wayward kid, who got caught up in Gotham’s street gangs. At this time, Terry parents were getting a divorce, and due to his age and the extenuating circumstance, a judge went easy on him, and he only got a handful of months in juvenile hall. This incident made sure Terry got “scared straight,” and he stayed on the correct path from there on out.
A few years later, when Terry is a senior in high school, he found himself on the run from the Jokerz gang, a group of street thugs who worshiped the long dead villain the Joker. McGinnis found refuge on the grounds of the old Wayne Manor, now home to an octogenarian Bruce Wayne, who lives in the old house alone with his dog Ace. Despite his age, Wayne is able to defend Terry from the Jokerz, although the effort places a great strain on his heart. McGinnis is able to bring Wayne inside his home and gives him his medication, and he falls asleep. Once making sure that Wayne is resting comfortably, McGinnis wanders around the house…and discovers the entrance to the Batcave. Wayne awakens, and furious that his secret past as Batman is exposed, forces Terry to leave the house.
Terry comes back home to a horrible scene – his father Warren McGinnis has been murdered, and from the looks of it, it was the Jokerz who committed the crime. Later, Terry discovers that Derek Powers, the CEO of Wayne-Powers (the company that merged with Bruce Wayne’s corporation Wayne Industries), is behind the murder, and only made it appear to be the handiwork of the Jokerz. Powers had ordered the elder McGinnis to create mass produced biological weapons for him, and when he refused, he had him killed.
Once Terry realizes Powers was behind his father’s murder, he goes to Bruce Wayne for help, but the old man doesn’t instantly jump at the chance to help him, citing his feeble age. Terry is despondent, and steals a high tech Batman suit, one of the last ones Bruce ever wore as Batman before retiring some two decades prior. Thanks to the Batsuit, Terry successfully brings an end to Powers' plan, exposing Powers to his own illegal chemicals, and thus transforming him into the villain Blight.
Bruce realizes that Terry McGinnis could indeed be the heir to the mantle of Batman that Dick Grayson and his other former Robins were not. McGinnis take on a job working for Bruce Wayne as his personal assistant and driver, but is in fact training with Bruce to hone his abilities as the new Batman. Although nowhere near the fighter Bruce Wayne is, the high tech Batsuit helps make up for his lack of proper fighting skills, and Wayne helps (from the safe distance of the Batcave) on all the forensics work. Eventually, the pair form a powerful bond, and McGinnis proves himself a worthy Batman. He even joins the Justice League of the future, at Superman’s request.
Several years after McGinnis started out as Batman, Terry learns the complicated truth behind his origins. One day, McGinnis has a confrontation with an elderly Amanda Waller, government operative and former leader of the Suicide Squad, who told Terry the whole truth - that she was behind not only his birth, but his becoming the new Batman as well. It was all part of a carefully orchestrated plan to create a new Batman, realizing Gotham still needed a Dark Knight as its defender once Bruce Wayne became too old for the job.
She confesses to McGinnis that Wayne is his biological father, as Waller used nanotechnology to ensure that Bruce Wayne's DNA overwrote the DNA in Warren McGinnis's reproductive cells. She planned to take things to their brutal conclusion and recreate the tragedy that drove Bruce into becoming the Batman, by hiring a killer to murder Terry McGinnis’ parents in front of him. But the hired gun grew a conscience, and refused. Nevertheless, fate stepped in when Terry was a teenager, and he became Batman after all. Even after all these revelations, Terry decides to stay on as Batman, realizing Gotham City needs its defender.
Terry McGinnis was a character created for animation, first appearing in the Batman Beyond animated series, which ran from 1999-2001. Eventually, much like Harley Quinn before him, he found a way into regular DC Comics continuity, where he finally appeared in 2014, and he has remained a part of it ever since.