Christopher Columbus
Christopher Columbus was a Genoese navigator and explorer who, amongst other things, discovered America in 1492.
While renowned for his discoveries, he was also a cruel man, who used American natives as slaves and, as a colonial governor, committed many atrocities. (AUDIO: Trouble in Paradise)
Encounters with the Doctor
During or before his fourth incarnation, the Doctor travelled with Columbus on the Santa Maria, and suggested that Columbus plot his course with an orange and a biro, but Columbus didn't listen. (PROSE: Eye of Heaven) At some point The Doctor acquired his business card. (TV: The Two Doctors)
The Sixth Doctor and Peri Brown later met Columbus in 1492 when they were summoned to his ship by the Doctor's eleventh incarnation. (AUDIO: Trouble in Paradise)
References
Ian Chesterton called Vicki "Christopher Columbus" when she ran off on her own to explore the Sagarro Desert on the planet Aridius. (TV: The Chase)
When discussing how certain the Fourth Doctor was about Zeos being hidden, he asked, "How could Columbus be so sure?" Romana replied, "Who?" (TV: The Armageddon Factor)
Ace unfavourably compared Raphael to Christopher Columbus when he failed to realise her intention to explore Kirith's Harbours. (PROSE: Timewyrm: Apocalypse)