Who was the only boxing heavyweight champion to stay undefeated during his professional career?

Answer 1

Rocky Marciano holds the record for the longest undefeated streak by a heavyweight and for being the only world heavyweight champion to go undefeated throughout his career. This record was challenged by Larry Holmes in 1985 when Holmes went 48-0 before losing to Michael Spinks twice. Light heavyweight Dariusz Michalczewski also challenged Marciano's record when he was 48-0, but lost to Julio César González in his 49th fight. Julio César Chávez holds the record for longest win streak with eighty-eight straight until he suffered a draw in 1993. Heavyweight Brian Nielsen tied Marciano's record but lost his 50th fight against Dicky Ryan. Willie Pep, a featherweight, had a perfect 62-0 record before he was defeated once, followed by a 72-0-1 undefeated streak. Packy McFarland was a lightweight (fighting between 1904-1915) who lost his first fight and then won his next 98, though he never won the lightweight title. Heavyweight champion Gene Tunney never suffered a defeat at heavyweight and retired as champion, although he did lose one fight at light heavyweight.