The Leader

In a parallel universe, the Leader was the President of the Republic of Great Britain and the third incarnation of the Time Lord known as the Doctor. (PROSE: Timewyrm: Revelation)

Biography
This universe's version of the Second Doctor selected one of the bodies offered to him by the Time Lords after his trial. Like his counterpart, this version of the Doctor was banished to Earth in the late 20th century, where he became the British President. (PROSE: Timewyrm: Revelation)

The Leader may have been at least partly responsible for his Earth's much more advanced technology. He died in the volcanic catastrophe that struck Great Britain in the aftermath of I-Day. (PROSE: The Face of the Enemy)

Behind the scenes
Photos of the BBC special effects designer Jack Kine were used to depict the Leader on the UNITY IS STRENGTH poster in the Technical Stores (the Doctor's hut on the regular Earth timeline) and the framed photograph on the wall of Brigade Leader Lethbridge-Stewart's office in Inferno. However, the Leader never appears on-screen in person and there is no on-screen evidence to suggest that the Doctor and the Leader had any connection; this connection was made only in the novels.