Damien Marchesseault (or Marchesseau) (April 1, 1818 – January 20, 1868) was a Canadian-born American politician who served as the seventh mayor of Los Angeles from May 9, 1859, to May 9, 1860, and then again from January 7, 1861, to May 6, 1865.

Born in St.-Antoine-sur-Richelieu, Quebec, Canada, Marchesseault was described as a carousing onetime New Orleans gambler.

[citation needed] During his term as Zanjero of Los Angeles (water steward), Marchesseault and a partner laid wooden water pipes that burst and turned streets into sinkholes.

Marchesseault killed himself on 20 January 1868, leaving a suicide note to his wife, Mary Clark Marchesseault, stating his motivation was shame from his drinking and gambling debts.

[1] Marcheassault Street in Los Angeles is named for him.