A by-election for the House of Commons constituency of Hartlepool in the former county of Cleveland, England, was held on 6 May 2021. The by-election was triggered following the resignation of Labour Member of Parliament (MP) Mike Hill, who resigned over allegations of sexual harassment. It was held on 6 May 2021 alongside elections to the Borough Council, Tees Valley Mayor, and Cleveland Police and Crime Commissioner. The seat is part of the "red wall", a set of constituencies that historically supported the Labour Party but where the party is being challenged by increasing Conservative support.