Mona Lisa
Earth's most famous painting, the Mona Lisa, was painted (multiple times) by Leonardo da Vinci.
History
In 1505, posing as a Human known as Captain Tancredi, Scaroth of the Jagaroth comissioned da Vinci to paint six copies of the Mona Lisa so that in 1979, as Count Scarlioni, he could steal the one known copy and sell the rest and so raise money to fund his time travel research. While the Doctor did not destroy the six "forgeries" (if, in fact, they could be considered forgeries, since they were all painted by Da Vinci), he did ensure that future X-ray machines would be able to discover their provenance by writing "THIS IS A FAKE" on the blank canvas of each. (DW: City of Death)
Many years later, one of the fakes had ended up at Leamington Spa Lifeboat Museum, and was placed along with several alien artefacts and other oddities in a secure section of the museum. (Leamington Spa Lifeboat Museum website)
