John Lawrence Sullivan (October 15, 1858 – February 2, 1918), also known as the Boston Strong Boy, was recognized as the first heavyweight champion of gloved boxing from February 7, 1881 to 1892, and is generally recognized as the last heavyweight champion of bare-knuckle boxing under the London Prize Ring rules. He was the first American sports hero to become a national celebrity and the first American athlete to earn over 1 million dollars.

He was born in Roxbury, Massachusetts (now a part of Boston) to Irish immigrant parents, Michael Sullivan from Abbeydorney, County Kerry and the former Catherine Kelly from Athlone, County Westmeath. Sullivan was nicknamed The Boston Strongboy. As a youth he was arrested several times for participating in bouts where the sport was outlawed, and he went on exhibition tours offering people money to fight him. In 1879, when he challenged anyone in America to fight him for $500, Sullivan had won over 450 fights in his career.

In 1883 - 1884 Sullivan went on a coast-to-coast tour by train with five other boxers. It was scheduled to comprise 195 performances in 136 different cities and towns over 238 days. To help promote the tour, Sullivan announced that he would box anyone at any time during the tour under the Queensberry Rules for $250. He knocked out eleven men during the tour.