William Allen (August 5, 1704 – September 6, 1780) was a wealthy merchant, attorney and chief justice of the Province of Pennsylvania, and mayor of Philadelphia during the colonial period. At the time of the American Revolution, Allen was one of the wealthiest and most powerful men in Philadelphia. A Loyalist, Allen agreed that the colonies should seek to redress their grievances with British Parliament through constitutional means, and he disapproved of the movement toward independence.