I was an amazing basketball player but I chose to be a boxer; You can surely say I was a Knockout artist...one of the best ever; That said, I always considered myself as a scientific boxer; I beaten 7 World Champions and 4 Hall of Famers; I never won a World Title but I won the vast majority of my fights and I only was stopped once in almost 300 fights; I hold some real impressive numbers as a record in the Heavyweight Division; Like others, I also managed to beat tough fighters such as Lou Scozza, the super tough Joe Sekyra and Jack Renault; My first name is William and I was born in the same Month and Year that the play "Peter Pan, Or The Boy Who Wouldn't Grow Up" premieres in London; Who am I?