William Mosforth (1859 – 11 July 1929) was an English football player who played either as an inside or outside left. Born in Sheffield he played for several Sheffield clubs but the majority of his career was spent at The Wednesday. He later joined Sheffield United, playing in their first season in existence before retiring in 1890 . He won nine caps for England between 1877 and 1882, which was a record at the time, scoring three goals for his country.