The Beast was created by the late Jim Henson as a friendly mascot for a line of instructional sex education materials.
Public schools strive to teach youngsters about sex before those troublesome "secondary characteristics" start to appear. (An exception is in the central United States, where sex education is done in churches by committees of adults suspiciously known as "laymen"; and in Dixie, where one generally doesn't put in for sex education until he is on his second wife, so to speak.)
In either case, what they never teach is that, once the change starts, it will ever stop. Every teenage boy has had nightmares about having to cut his startling tuft of pubic hair with hedge clippers twice a day to keep it from emerging out his pant leg; also of thereby occasionally severing his penis, which by then hangs below the knees (when it isn't waving hello out his collar).
Henson created the "Beast" series of sex-education books, adapting the successful Cookie Monster, to reassure young boys that there is nothing inherently wrong with becoming completely simian, having gross blue hair all over one's body, being more gawky, clumsy, and horny with each passing day, and dragging girls by the ears into closets and guest rooms for a little inept, unwanted rubbing.
Young girls, of course, have similar fears based on imagining a limitless continuation of the changes they are experiencing. Henson created a line of educational materials for them, called Hindenburg. It was derived from breast-expansion hentai from Japan. It was much later that Henson found a way to work the related genre of tentacle rape into the coursework.
The early years
The Beast coped with a father who loved children a little too much, a nonexistent mother, and a horrible bout of hair-ball coughing every goddamn morning. Upon acceptance into one of the nation's finest private schools, The Beast became an invaluable asset to human-mutant-fluffy relations. In his spare time, he washed dishes and mowed lawns to pay for therapy for his addiction to hair wax.
Throughout adolescence, he had an active social life, becoming the life of the party with his ability to calm people down with his soothing voice and superior intellect, fire people up with his acrobatics, and hang from the ceiling to do kegstands. Other partygoers would merely watch in fear and awe.
But he grew increasingly distraught with his inability to pick up chicks. While they all said they liked him as a friend and laughed at his jokes, they all said they weren't into "the furry thing." After graduating high school, Beast traveled through Europe--problem solved!--before his first semester at Oxford University.
Fraternities have always been pretty shady, but the Beast joined Omega Omega Omega, the drinking man's fraternity. He fit in instantly, as Pledge Week back then involved holding pledges down and shaving their entire bodies. Now he looked normal, except for his ears, which all the girls found cute, but not cute enough to suck on.
As the years went by, he achieved acclaim for his many papers and research projects, even becoming the youngest man and only shaved-mutant to win the Nobel Peas Prize for his humanitarian work. He graduated summa cum laude while keeping it to a whisper. And he often laughed, even if you didn't, just now.
The Beast traveled to France soon after, deciding at last to challenge fate and find love in a place that hates Americans and muppets. There, he first found work at a bakery, until destiny appeared, in the form of a sexy little number named Belle who came in to the shop one day, complaining about blue hair in her baguette. They struck it up immediately and soon wed and had six blue monster-children. These they sent back in time to become the missing links, but that's another story.
Twenty years of marital bliss passed by, with Beauty and The Beast loving each other more every day. They went for moonlit walks, they wrote each other poems, and they experimented with anal. They were in love. Then one day, as so often happens, Belle up and died. No, seriously, she stood up, and then dropped to the floor. Outraged, saddened, and sure he would be blamed, the Beast abandoned personal grooming and threw away his razors. (Kind of like your wife did, about three years in.) Public reaction to this only made the problems worse, and the Beast fled the country.
His return to America opened a new door in history. He had hoped to participate in new sex-education pamphlets brought up-to-date with all the latest fetishes. However, sex education was no longer being performed in America. The national teachers' union had adopted an official policy that "kids are going to have sex, no matter what we say"--and a fallback strategy of easy access to flavored condoms and sexual lubricants. This was pioneered in KY, OH.
A despondent Beast boarded a bus, unsure of where to turn now to restart his career. In reaching his seat, however, he tripped over a man in a wheelchair. He insulted the "cripple" and harsh words and threats of lawsuit followed--then, serendipitously, the two saw one another as fellow social misfits and decided to form a partnership, an organization that would eventually become the storied X-men. For that was no ordinary "cripple," but Professor Xavier, who would go on to prod the Beast into suicidal missions with inscrutable remarks, matchbook philosophy, and a wry smile.
Oh sure, regular human doctors operating on their family and friends is pretty routinely discouraged by most hospitals, and in an ideal world devoid of bigotry a doctor wouldn't refuse service to a patient just because they shoot kinetic beams out of their eyes uncontrollably, which makes fitting them for ruby contact lenses a bit hazardous. Or because they can read their physicians mind and know they've been cheating on their spouse with a nurse and know all their passwords and credit card numbers. Nor because the patient happens to look like a demon and smell like brimstone, and the physician claims this goes against their religion. Unfortunately, the X-Men don't live in such a happy go lucky utopia devoid of social ills, where everyone's as nice and understanding as Dr. Moira Mactaggert. So whenever Jean Grey's too busy being dead or mind controlled into being evil that week to be the team's attending physician, the duty of being the team's M.D. falls onto Beast instead. The X-Men never have to worry about getting blue hair in their wounds though, as Dr. McCoy makes sure to wash and glove up his clawed hands and feet each time before preforming surgery or examining anyone's prostate.