Name: Billy Dempsey
Birth Name: William Dempsey
Died: 1888-01-22 (Age:22)
Hometown: Brooklyn, New York, USA
Boxing Record: click
William 'Bill' Dempsey died from injuries sustained in a bout with Simon Besser 22 Jan 1888, at Brooklyn, NY, USA, after he was knocked out.
Source: Death under the Spotlight: The Manuel Velasquez Boxing Fatality Collection: 
Also reported as John Dempsey, July 10, 1888, at Fort Hamilton, NY. Source: December 1900 Philadelphia newspaper article.