Десятый Доктор
Somewhere in his life he crashed his TARDIS into the TARDIS of the Tenth Doctor and consequently nearly opened a "Belgium sized" black hole because of the paradox caused, which the Tenth Doctor also uses to explain the notably aged appearance of his former self. However the Tenth Doctor, remembering the event, knew how to stop it because he recalled watching himself correct the mistake when he was the Fifth Doctor. ("Time Crash")