A good one, it's worth a listen is Johan Orsolics who was an Austrian EBU welterweight champion who was thisclose to a shot at Jose Napoles for the world title but managed to get himself knocked out by... I forget now but this is a good one from a singing boxer.
Jack Doyle 'the Gorgeous Gael' fought and lost to Jack Petersen for the British Heavyweight title in 1933 having allegedly warmed up in the pub first. His ex wife Movita an actress who appeared in Mutiny on the Bounty married Marlon Brando.
Jack also sold out the London Palladium when he appeared there as a singer...
There's few videos of his career, life and downfall on YouTube and I have a particular interest as I picked up the original contract for his debut fight which, if they ever make a film of his life, which has been spoken about, will be worth a fortune...............I hope
Lionel Rose (21 June 1948 – 8 May 2011) was an Australian professional boxer who competed from 1964 to 1976. He held the undisputed WBA, WBC, and The Ring bantamweight titles from 1968 to 1969, becoming the first Indigenous Australian to win a world title.
During his time off from boxing in the 1970s, Lionel embarked on a modest singing career in Australia having hits with "I Thank You" and "Please Remember Me" in 1970. The country and western song "I Thank You" was a top 5 nationwide hit.
Here's the song with a montage of Lionel's career: