U1
- 1 (disambiguation)
- 1924 United States Army Air Service aircraft designation system
- 1962 United States Tri-Service aircraft designation system
- 1U (disambiguation)
- Apple U1
- Avro 504
- De Havilland Canada DHC-3 Otter
- German submarine U-1
- Gitaroo Man
- HDMS U-1
- LNER Class U1
- Oberursel U.I
- SM U-1 (Austria-Hungary)
- SR U1 class
- Secure Digital
- Soviet Union military aircraft designation systems
- U (disambiguation)
- U-1-class submarine (Austria-Hungary)
- U1 (Berlin U-Bahn)
- U1 (Frankfurt U-Bahn)
- U1 (Hamburg U-Bahn)
- U1 (Munich U-Bahn)
- U1 (Nuremberg U-Bahn)
- U1 (Vienna U-Bahn)
- U1 Technology
- U1 spliceosomal RNA
- UI (disambiguation)
- UL (disambiguation)
- UNIONS 1
- Unemployment
- Yuvan Shankar Raja