Major Thomas Henry Gem (21 May 1819 4 November 1881), known as Harry Gem, was an English lawyer, soldier, writer and sportsman. Alongside his friend Augurio Perera, he is credited as the earliest inventor of the game of lawn tennis. Gem was born in Birmingham and educated at King's College London. From 1841 he practiced as a solicitor in Birmingham, becoming a magistrate's clerk in 1856. Highly active in local life, Gem wrote journalism and drama for several local publications, rose to the rank of Major in the 1st Warwickshire Rifle Volunteer Corps and was active in numerous sports including cricket and athletics. He is recorded as having won a bet by running the 21 miles from Birmingham to Warwick in under three and a half hours.