Dr. Noonien Soong.
Dr. Noonien Soong (played by Brent Spiner) was one of Earth's leading cyberneticists, who lived on the colony of Omicron Theta, where he created several androids with positronic brains, the last two being Lore and Data. (TNG: "Datalore")
He was thought to have been killed in the Crystalline Entity's attack on the colony, when this massacre was uncovered in 2364. Three years later, however, he was discovered alive in the jungle of Terlina III, where he had continued his work to create a perfect emotion chip. Dr. Soong was killed that same year by his own creation, Lore. (TNG: "Brothers")