The Leader

In a parallel universe, the alternate version of the Third Doctor (known to humans by the title of The Leader) was the President of the Republic of Great Britain.

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, he was banished to Earth in the late 20th century, where he managed to become President of Great Britain.

He 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. (PDA: The Face of the Enemy)