For Pete's Sake

Who is Pete? Does anyone know? I have heard that it meant Saint Peter, but I'm not sure I'm buying it.

FOR PETE'S SAKE - The phrase is simply a polite version of a common and profane expression involving the name of Christ. We'd surmise that the original 'Pete' was St. Peter." From Morris Dictionary of Word and Phrase Origins by William and Mary Morris. Substituting less offensive words - like Godfrey Daniel for the other GD - is called a Minced oath.