Joseph Aloysius Wambaugh, Jr. (born January 22, 1937in East Pittsburgh, Pennsylvania) is an American writer known for his fictional and non-fictional accounts of police work in the U.S.

Wambaugh's unique perspective on the realities of police work comes from experience: he is a former Los Angeles policeman and detective. In 1970 his first novel, The New Centurions, was published to critical acclaim and popular success. Soon turning to writing full-time, Wambaugh was prolific and popular through the 1970s, mixing novels (The Blue Knight, The Choirboys, The Black Marble) with non-fiction accounts of crime and detection (The Onion Field). In contrast to previous, heroic fictional policemen, Wambaugh brought a gritty texture to his flawed police characters. Many of his books were made into movies, and his realistic approach to police drama was highly influential in both film and television depictions.

Wambaugh's most famous non-fiction book is the Blooding, which tells the story behind how DNA fingerprinting helped solve two murders in the English Midlands, resulting in the arrest and conviction of Colin Pitchfork.

In 2004, Wambaugh was the recipient of the Mystery Writers of America Grand Master award.