Allan Pinkerton on horseback during the Battle of Antietam

Allan Pinkerton (1819–1884) was a Scottish-American detective and the founder of the Pinkerton National Detective Agency, which became one of the most famous private detective agencies in the United States. Born in Glasgow, Scotland, Pinkerton immigrated to the U.S. in 1842 and initially worked as a cooper (barrel maker) before becoming involved in law enforcement.

In 1850, Pinkerton founded the Pinkerton National Detective Agency, which provided a variety of investigative services, including criminal investigations, private security, and the tracking of criminals. The agency became known for its ability to infiltrate criminal organizations and for its role in investigating and preventing crimes. Pinkerton and his agency were involved in several high-profile cases, including the capture of criminals like Jesse James and the gang of the James-Younger outlaws.

During the Civil War, Pinkerton served as the head of the Union Intelligence Service, acting as a chief spy for the Union Army. His agency also became known for providing protection for railroads and businesses, as well as for its involvement in labor disputes, often siding with employers during strikes.

Pinkerton's legacy is marked by both his success in solving crimes and his controversial tactics. The Pinkerton Agency played a significant role in shaping the development of modern American private detective work and security services. After his death in 1884, the agency continued to operate under the leadership of his successors and became a major force in American law enforcement.