Leonardo da Vinci (April 15, 1452 – May 2, 1519) was a Human who lived on Earth during the 15th and 16th centuries. A major figure in Earth's renaissance period, da Vinci was among many other things an inventor, artist, and writer.
The crew of the USS Enterprise met a man named Flint in 2269, an immortal being who had lived on Earth for thousands of years. During Flint's long life, one of his identities was that of Leonardo da Vinci. (TOS episode: "Requiem for Methuselah") However, his claim to have met da Vinci was considered somewhat dubious by the 24th century. (VOY episode: "Scientific Method"; TOS novel: No Time Like the Past)
Around 2349, when he was eight years old, Julian Bashir read a biography of Leonardo da Vinci, learning how to create a "memory cathedral" in his mind just as da Vinci had done. (DS9 novel: Cathedral)
In 2373, Captain Kathryn Janeway began running a program in which she played the role of apprentice in da Vinci's workshop aboard the USS Voyager. (VOY episodes: "Scorpion Part I", "The Raven", "Scientific Method")
An official Starfleet/Daystrom Institute PADD of Data's internal and external workings (to the android's own flattery) had an introductory diagram of him in the style of da Vinci's Homo universalis ("Universal Man") sketch. (TNG novel: Immortal Coil)