Lawyer from Fredrick, Maryland who wrote The Star Spangled Banner during the War of 1812. He had gone aboard a British ship in Baltimore harbor under a flag of truce--not as a captive--to negotiate for the release of an American who was being held captive. From the truce ship, he had an excellent view of the Battle of Baltimore being fought at Fort McHenry. As the sun rose, he saw that Old Glory still flew over the fort, and he was moved a few days later to jot down a few lines about it. The rest, as they say, is history.
Many things in and around Baltimore are named for Key. He also had a second cousin three times removed named after him, one Francis Scott Key Fitzgerald, who later became famous under the shortened handle F. Scott Fitzgerald.