Joshua A. "Josh" Leach (May 8, 1843 – June 28, 1919) was an American locomotive worker and trade union functionary. He is best remembered as the founder of the Brotherhood of Locomotive Firemen (B of LF) in 1873 and head of that organization from 1873 to 1876. Traveling to Terre Haute, Indiana, on behalf of the firemen's order in February 1875, Leach inspired the 19-year-old Eugene V. Debs to become active in the organization, leading to his election as Secretary-Treasurer in 1880 and starting him on a career as a trade union organizer.