David J. Cook (1840 – April 2, 1907) was an American law enforcement officer known for his service as a sheriff and detective in the 19th-century American West. Born in Indiana, he later moved to Colorado, where he worked for decades in Denver and surrounding areas. Cook gained respect for his efforts in fighting crime, pursuing fugitives, and maintaining order on the frontier. He served as sheriff of Arapahoe County and led several successful manhunts. His career reflects the challenges and achievements of law enforcement during the Western frontier period.