The 1938 Barnsley by-election was a by-election held on 16 June 1938 for the British House of Commons constituency of Barnsley in what was then the West Riding of Yorkshire. The seat had become vacant on the death in April 1938 of the Labour Member of Parliament (MP) John Samuel Potts, who had represented the constituency since the 1935 general election, having previously been Barnsley's MP from 1922 to 1931.