D class
- British D-class submarine
- Class D (disambiguation)
- D type (disambiguation)
- D-class Melbourne tram
- D-class Sydney tram
- D-class blimp
- D-class cruiser (Germany)
- D-class cruiser (United Kingdom)
- D-class destroyer (disambiguation)
- D-class ferry
- D-class lifeboat
- D-segment
- DHR D Class
- Delta class (disambiguation)
- LNWR Class D
- MRWA D class
- Metropolitan Railway D Class
- NBR D class 0-6-0T
- NZR D class (1874)
- NZR D class (1929)
- SCP Foundation
- SECR D class
- United States D-class submarine
- WAGR D class
- WAGR D class (1884)
- WAGR D class (diesel)