The Other 14th Doctor and Bessie
After what should have been the death of the Thirteenth Doctor, the Time Lords decided that the universe needed the Doctor. The granted him further regenerations that were the younger parts of a previous regeneration. But here, because of the death of the Time Lord Blinovitch, in the Great Time War that spanned the end of the Eighth Doctor's time and the beginning of the Ninth, divergent timelines have begun to intermix. The Thirteenth Doctor was a younger version of the fourth, but in a divergent timeline, the Time Lords decided that a younger version of the Third Doctor would be more useful, and the Other Fourteenth Doctor was created. He operates throughout the universe, carrying Bessie with him in the Tardis Garage.
Bessie is a $10.00 Flea Market Find. She was made by RemCo as part of some series I don't remember, and came originally with a cardboard cut-out driver.