U-9

U-9 or U9 may refer to:

* German submarine "U-9", the designation of several German U-boats
* U-9, a U.S. Army designation for the Aero Commander (aircraft), a light twin-engined aircraft
* U9, the IATA code for Tatarstan Airlines
* U9 (Berlin U-Bahn), a subway line in Berlin, Germany
* U9, a model of the Motorola ROKR cell phone