Peter Hains (born January 9, 1872) was an Army Captain convicted of killing his wife's lover. The case became a sensational murder trial in New York City in 1909. Abetted by his brother, sea novelist Thornton Jenkins Hains, Peter Hains gunned down prominent magazine editor and Harper's contributor William Annis at the latter's yacht club in Bayside, Queens. The crime, known as the Hains-Annis Case or the "Murder at the Regatta," played an important role in the development of criminal and matrimonial law. Peter Hains was convicted of manslaughter and received an eight-year sentence. His brother was initially acquitted but later convicted on retrial before finally receiving a pardon from the governor of New York.