Henry McCoy was a child prodigy, having graduated Harvard at age 15. He was eventually recruited to work as a researcher for the CIA's "Division X", wherein he investigated supersonic flight and built the Cerebro prototype. One day, he was approached by the Man in Black, Charles Xavier, Erik Lensherr, Moira MacTaggert, and Raven Darkholme during the early formation of the X-Men as a black ops group. When Charles accidently exposed him as a mutant, the urbane Hank displayed his physical mutation of prehensile feet and agility; greatly impressing Raven. He became instantly smitten with her, and a budding attraction was evident between them. Hank revealed that he had been working on a serum to cure his physical mutation but leave his abilities intact. He believed that Raven's ability to alter her appearence would hold the key to perfecting it. He requested a sample of her blood, during which they shared each others' wish to appear "normal" as well as a kiss. However, Erik's constant validation of her true beauty and self overturned her opinion, and when Hank finished the serum she refused to take it. He returned to his lab and injected himself and his animal-like feet seemed to revert to normal. However, they quickly changed back and McCoy underwent a radical transformation which resulted in him manifesting blue fur all over his body and taking on a more beastial appearence with the addition of fang-like teeth, pointed ears, and claws. The serum had the opposite effect he'd intended, it enhanced his mutation instead of dampening it. After trashing his lab, he left a note and a box containing the team's suits and met them at the hanger holding their stealth jet of his design. Mystique remarked that he was "beautiful" and this was "truly who he was meant to be." After lashing out at Erik when he remarked "Never looked better", Hank was given the codename "Beast" by Havok. He piloted the team to stop Sebastian Shaw from starting WWIII between the US and the Soviet Union during the Cuban Missile Crisis. After they crashed on a nearby beach, he and Havok battled Azazel until Lehnsherr managed to infiltrate the Hellfire Club's damaged submarine and kill Shaw. When the remaining mutants left to form the Brotherhood of Mutants with Lehnsherr, Raven told a saddened Hank to remember to be proud that he was a mutant before being teleported away.
As an expert of the Mutant Affair, Dr. Hank McCoy appears in a tv show along with "Mr. Shaw", who is presumably Sebastian Shaw or a descendant, debating on the necessity of registrating the mutant citizens. McCoy declares that a registration act is not a possible solution and defends the rights of the mutants, as well as proposing a peaceful way of cohabitation between mutants and humans.
After graduating from the Institute, Hank McCoy becomes the Secretary of Mutant Affairs in the U.S. Government. When Magneto and Callisto join forces and attack the truck in which Mystique was held prisoner, McCoy becomes acknowledged of the existence of a "cure" for mutants developed by Worthington Industries' Dr. Kavita Rao. He visits the facility and meets Jimmy, a mutant whose DNA is the fount of the cure. Later, he comes back to his old school, Xavier's Mansion, to warn his ex teammates about the threat that the cure represents. Dr. McCoy says he could understand why some mutants would want to be free of persecution, citing his lingering desire to be normal.
Once the weaponization is made without his knowledge, McCoy resigns from his position in the government and returns to Xavier's mansion, where he feels he should be due to his principles. When Professor Xavier is killed by the Phoenix, Beast attends his former mentor's funeral. He is then contacted by Wolverine, who has discovered that Magneto is heading to Alcatraz Island to kill Jimmy and destroy the cure. Beast joins the team and participates in the battle at Alcatraz, donning his old uniform and commenting on how it feels smaller than before. During the fight, he seems to revert to a more primal state, often roaring as well as defeating his opponents with a savage fighting style. While Wolverine is acting as a distraction, Beast ultimately injects Magneto with the cure, so rendering him powerless. After the battle, McCoy is appointed by the President as the United States ambassador to the United Nations.
Dr. McCoy is a brilliant scientist and researcher. One of the earliest recruits to the X-Men, McCoy proved invaluable both on the field of battle, and in the laboratory, where his vast intelligence and insight into mutant genetics quickly distinguished him from the rest of the team. Dr. Henry McCoy took the name of "Beast" after the nickname he'd gained during his college football years. Despite his surprising strength, agility and talent as a fighter, he prefers his refined intellect to his brutish fists when attacking a problem.
As a talented negotiator and diplomat, Dr. McCoy is the first known mutant to hold a position in the United States government, with the Department of Mutant Affairs. As an advisor to the President, Hank McCoy does his best to ensure the government's mutant policies are as informed and fair as possible. He is at once embarrassed by and defensive of his mutant nature, but he believes humans and mutants are capable of living together in peace, and will fight to preserve that vision.