I have had two vicious ball pythons- a het pied and a het albino (a male and a female respectively) and I have had two others that will bite but are clearly mostly timid, not outright aggressive- they are a black pastel male and a pastel female.

I have never been bitten by a ball python, though- I am very careful with them. I have been bitten by a Brazilian Rainbow Boa, and my baby Jungle Carpet nips a lot but it's cute