The Unknown Quantity
- År: 1919
- Land: United States of America
- Sjanger: Drama
- Ettromsleilighet: Vitagraph Company of America
- Nøkkelord: lost film
- Regissør: Thomas R. Mills
- Cast: Corinne Griffith, Huntley Gordon, Harry Davenport, Jack McLean, Jack Ridgeway, F.R. Buckley