Fat Bastard was a grossly overweight, obnoxious Scotsman and Dr. Evil's spy within the Ministry of Defence. He acquired the nickname "Fat Bastard" due to his obesity and the fact he was born out of wedlock (or so he claims). Fat Bastard is the one who stole Austin Powers' mojo in 1969 from his cryogenically frozen past self in the M.O.D.'s Celebrity Ward, thus rendering Austin of the future powerless to attract the opposite sex.
In 1999, after Austin had gone back in time to 1969 and then returned with Felicity Shagwell, Fat Bastard, despite being rich from the money that Dr. Evil paid him, broke into Austin's shag pad and attempted to do him in, nut was defeated thanks to a swift kick in "the pills" by Felicity.
Fat Bastard would return however, and continue working for Dr. Evil, acting as his liason with Roboto Industries president Mr. Roboto in Japan. There, Fat Bastard became a champion sumo wrestler to forget his weight problems, but a second encounter with Austin, this time with Foxxy Cleopatra, convinced him to quit Dr. Evil's employ and turn good. He then went on "the Subway diet" and lost all of his weight.