Philip Barton Key (April 12, 1757 – July 28, 1815) was a Representative from the third district of Maryland, and later a United States federal judge. Unusually for a politician in the early United States, Key had been a Loyalist in the American Revolution. Born in Charleston, Cecil County, Maryland, Key pursued an academic course. During the War of Independence he served in the Maryland Loyalists Battalion as a captain. He fought with the British Army from 1777 to 1781, until he was captured by the Spanish in Pensacola, Florida with the rest of his battalion. He was kept as prisoner for a month in Havana, Cuba, before being paroled and sent to New York City until the end of the war.