James Mulcahy (11 January 1858 – 17 July 1915) was a Canadian-American architect active primarily in Boston, Massachusetts, and the surrounding area from at least 1888 until his death in 1915. He served as Boston Building Commissioner from 1903 to 1906. He collaborated for many years with his nephew and fellow architect James E. McLaughlin, who designed Fenway Park, home stadium of the Boston Red Sox baseball team.