President

President was the title given to the heads of state, usually of a republic, or the figure who presided over a governmental or corporate body. There were Presidents on many worlds, including Gallifrey, Earth, Androzani Major and Fangoria. (DW: The Deadly Assassin, The Sound of Drums, The Caves of Androzani, PDA: Warmonger)

On Gallifrey, the Lord President of the Time Lords was the head of Gallifreyan society. (DW: The Deadly Assassin) Androzani Major was similar, having a single President as the planet's lead official. (DW: The Caves of Androzani)

On Earth, the United States of America was governed by a President. (DW: The Chase)

Throughout its existence during the American Civil War from 1861 to 1865, the Confederate States of America was likewise governed by a President. The only person to ever hold the office was Jefferson Davis. (TN: Blood and Hope)

In Pete's World, Great Britain had a President. (DW: Rise of the Cybermen) By the 26th century, the whole of Earth had a President. (DW: Frontier in Space, BFC: Terror)