Pai Mei is a Kung Fu Master who as legend has it, has lived for at least 1000 years, perfecting his art of Bak Mei and passing it on to those who survive his training.He was found by Bill at some point in the past, and he trained Bill as his student. Pai Mei is totally dedicated to his art, he is a fighter, and for him right and wrong does not go farther than Honor and Pride. So unlike Hatori Hanzo, he does not particularly despise or hate Bill, and trains all of Bill's students, including Beatrix, Elle and (it is implied), the other members of the Deadly Viper Assasination Squad.Bill told the legend about how Pai Mei was walking down the road when a Shaolin Monk came from the opposite direction. Pai Mei was feeling generous, so he nodded (ever so slightly) to the Monk, but this generous social gesture was unreturned. He then went to the Shaolin Temple, and demanded that his Honor be restored. The head of the Temple tried to console him, but he could not be, and so began the Massacre of The Shaolin Temple.Pai Mei as it turned out, was killed by Elle. He had snatched out her Right eye after she called him a Worthless Old Fool . Knowing she could never defeat him in a fight, she poisoned him.For the real life Pai Mei (Or Bak Mei, his real name), please see the article in wikipedia: http://en.wikipedia.org/wiki/Bak_MeiThe accounts of this person vary greatly, although for the purposes of the film, Pai Mei the character has been in several Kung Fu movies, dating back to the 70's.