Irish preacher, born in West Tyrone. He was stationed at Clones in 1786. Volunteering for the West Indies, he was ordained deacon and elder by Wesley at the Manchester Conference in 1787, but his appointment to St. Eustatius was thwarted by the Dutch governor of the island. Instead he served in Antigua 1788-1791, Tortola 1791-1793 and St. Kitts 1793-1794. He was one of Mary Bosanquet Fletcher's correspondents. He married while in Antigua, but left for America in 1794 because of his wife's health. After her death in Boston he attended the Conference in Connecticut in July 1795, was accepted as a preacher in the American connexion and reordained as an elder the following year. He informed Asbury of Thomas Rankin's influence on Wesley against Asbury and America.
With Asbury's support he was given prestigious appointments in Northampton, Baltimore City and Charleston, where he married for the second time and faced hostility for his opposition to slavery. In 1801 he bought a site in Columbia, SC on which Washington Street Methodist Episcopal Church was built in 1804. He retired from the itinerancy in 1803 and helped to found Mount Bethel Academy, a South Carolina Conference school in Newberry County. He died in 1815.
His son William Harper (1790-1847) was a prominent pro-slavery advocate who became Chancellor of South Carolina.