The Toughest Boxers to Ever Enter the Ring

Kilrain came from boxing’s bare-knuckle era, where toughness was everything. He fought for hours if needed, enduring unimaginable punishment. He had no quit in him, thriving in grueling, bloody battles that broke lesser men. Kilrain’s willingness to suffer made him one of the toughest fighters of the 19th century.

In 1889, Kilrain battled John L. Sullivan in a legendary bare-knuckle fight that lasted 75 rounds. Though exhausted and battered, Kilrain kept standing and swinging until his corner finally stopped it. That marathon showed astonishing toughness — enduring punishment for over two hours against the most feared man of his era.