The Birth: The Beast's father, Norton, woked in a nuclear power plant and was exposed to high dosses of radiation. When he and his wife, Edna, had a child (Hank), his only flaws at birth was over developed hands and feet (the doctors expected some sort of monster).
Stan Lee and Jack Kirby are credited for bringing this hero to the world in his first historic appearance in X-Men #1, September 1963.

The Alter Ego: Beast's real name is Hank McCoy. He grew up in Duffee, Illinoise with his father; Norton and mother; Edna McCoy. Hank possesed great strength and intelect, and in high school became valid victorian, and captain of the football team (he even got an offer from the Dallas cowboys!). His appearance is quite deceptive since he is the intellectual type and abhors unnecessary violence. Infact Beast is all for settling problems with peace rather than using his mighty fists. And Beast has become a well respected Bio-chemist and a doctor besides being the hero he is.

The Legend: Beast was born with abnormally large hands and feet due to radiation that had affected his father who worked in a nuclear plant. He had a good childhood, excelling on the sports feild and the classroom. Later on, named "El Conquestador" deduced Hank as being a mutant and kidnpped his parents. Fortunately, the X-Men were also on the lookout for him. They caught up with the villain and Hank was able to resue his parents. After this, Hank McCoy joined the X-Men.
Later on, Hank left the X-Men for a short time to pursue his scientific experiments. After a break-in at his lab, he was forced to hurry an experiment which he was fearful of falling in the wrong hands. He tried to cure himself but instead the experiment failed and he ended up with thick grey fur all over his body. The fur later turned to blue. That's probab;y why he got the name "Beast".
Beast later joined the Avengers. He's also been on the team with the Defenders as well as the X-Factor. The public later demanded closure of the X-Factor so Hank returned back to the X Mansion with the X-Men.
Beast's powers include great agility, strength, intelligence and stamina. He also has creepy looking fangs and really big claws.

X-Men #1