The Unknown Quantity
- Tahun: 1919
- Negara: United States of America
- Aliran: Drama
- Studio: Vitagraph Company of America
- Kata kunci: lost film
- Direktur: Thomas R. Mills
- Pemeran: Corinne Griffith, Huntley Gordon, Harry Davenport, Jack McLean, Jack Ridgeway, F.R. Buckley
