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. (TV: The Deadly Assassin, The Sound of Drums, The Caves of Androzani, PROSE: Warmonger)

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

On Earth, the United States of America was governed by a president. (TV: 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. (PROSE: Blood and Hope)

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

In a parallel universe visited by the Third Doctor, the American Confederation was led by a president. (PROSE: The Face of the Enemy)

During a crisis of frozen planes in mid-air, UNIT head Kate Stewart got a call from the President, possibly the American one, but had to call him back later. (TV: The Magician's Apprentice)