Dora (Frontier in Space)

The President of Earth in 2540 was a female closely advised by Earth's primary military officer, General Williams, a former friend of hers.

After a series of raids of Earth cargo ships, believed to be the work of Draconia, she personally met with the Draconian Emperor's son in order to negotiate an end to hostilities. She came under pressure from both her military advisors and the political opposition to take military action against Draconia. Eventually, perhaps because of the threat of a military coup, she agreed to break off diplomatic relations. However, she refused to fire the first shot in a war.

Thanks to the Doctor, it was revealed that the raids were the actions of Ogron mercenaries and war was averted. (DW: Frontier in Space)
 * ''According to the novelisation, she was not the first female to hold the office.