David J. Cook (1840/1842 [1]– April 2, 1907) was an American western lawman and City Marshal of Denver, Colorado, responsible for over 3,000 arrests.

Growing up, he worked as a farmhand before moving to Kansas in 1855, and then in 1859 to Gilpin County, Colorado, looking to prospect for gold.

In 1861 he joined the Colorado Cavalry upon the outbreak of the American Civil War, and was later assigned to counterespionage for the Union Army, tracking Confederate spies, investigating gold smuggling and similar crimes.

Having subsequently transported Musgrove to jail in Denver, Cook cleverly predicted his partner Ed Franklin would attempt a rescue.

It is rumored to have been ghostwritten by Thomas F. Dawson,[2] editor of the Denver Times and personal secretary to Senator Henry Teller.