Sir Walter Raleigh discovered the potato. The Third Doctor told Jo Grant that he had once shared a cell with Raleigh in the Tower of London and that he spoke endlessly of the vegetable. (TV: The Mind of Evil)
Raleigh was released from the Tower in March 1616 and arranged for William Shakespeare to be poisoned. The playwright died in Stratford-upon-Avon only five weeks later. (PROSE: The Empire of Glass)
He visited Roanoke Island in 1590 and saw the TARDIS. He studied it after a while he pressed the fast return ship and sent it back 400 years with him in it which created the Children of Croatoan, but the Sixth Doctor negated that timeline by getting Wanchese to knock him out and press it instead. (AUDIO: Voyage to the New World)
In 1879, Queen Victoria referred to Sir Robert MacLeish as "her" Sir Walter Raleigh. (TV: Tooth and Claw)
Behind the scenes
Raleigh was portrayed by Richard Todd in The Virgin Queen and Simon Jones in the Blackadder II episode "Potato".