Pinkerton, founded as the Pinkerton National Detective Agency, is a private security guard and detective agency established in the United States by Scotsman Allan Pinkerton in the 1850s.

Pinkerton became famous when he claimed to have foiled a plot to assassinate president-elect Abraham Lincoln, who later hired Pinkerton agents for his personal security during the Civil War. Pinkerton's agents performed services ranging from security guarding to private military contracting work. The Pinkerton National Detective Agency hired women and minorities from its founding, a practice uncommon at the time. Pinkerton is the largest private law enforcement organization in the world.