Benny Leonard
Born in New York City on April 7th, 1896, Benjamin Leiner, later known as Benny Leonard, was the child of Orthodox Jews and learned to fight on the streets. His parents did not understand his desire to fight, and when Leonard entered the ring professionally at the age of 15, he used the pseudonym Benny Leonard to keep his boxing a secret. To avoid visible bruises, Leonard developed a smart, defensive boxing style. Leonard rose to the top of his division, and defeated Freddie Welsh to become the 1917 World Lightweight Campion.
In a controversial and emotional match against Jack Britton for the 1922 welterweight world championship, Leonard was disqualified for striking Britton while he was down. Throughout his career, Leonard became a symbol for the acceptance of Jews into American communities. He also inspired many young Jewish boys to take up boxing. At the wish of his mother, Leonard retired from boxing in 1925, but later attempted a comeback in 1931. He was thwarted by a defeat at the hands of Jimmy McLarnin in 1932. Following his retirement, Leonard refereed boxing matches. In 1947, he died from a heart attack during a match. Benny Leonard was inducted into the International Hall of Fame in 1990.
Source: http://www.jewsinsports.org/profile.asp?sport=boxing&ID=8