The android officer on the Enterprise-D is Data. He serves aboard the USS Enterprise-D in Star Trek: The Next Generation as its second officer and chief operations officer, making him one of Captain Picard's senior bridge officers.
Data is a Soong-type android created by cyberneticist Dr. Noonien Soong. He was discovered on the colony world Omicron Theta after the Crystalline Entity destroyed the settlement, and later joined Starfleet. His positronic brain gives him exceptional analytical and computational abilities, but he spends much of the series trying to understand human emotion, humor, art, and social behavior.
A common mix-up is confusing Data with Lore or B-4. Lore is Data's older, unstable android brother, while B-4 is another Soong android with less advanced programming. Data is also not the ship's captain or chief engineer: Jean-Luc Picard commands the Enterprise-D, and Geordi La Forge leads engineering. Data's distinctive gold complexion and calm, literal manner make him one of television's best-known fictional androids.