Boysen may refer to:
- Boysen Reservoir in the U.S. state of Wyoming
- Andrew Boysen, American composer
- Audun Boysen, Norwegian middle distance runner
- Gudrun Boysen, Danish physician
- Hans-Jürgen Boysen, German football player and manager
- Harro Schulze-Boysen and Libertas Schulze-Boysen, German resistance fighters against the Nazi regime
- The boysenberry, a hybrid created by American horticulturist Rudolph Boysen