D1
- 152 mm howitzer M1943 (D-1)
- 1D (disambiguation)
- AEG D.I
- ATC code D01
- Albatros D.I
- Aviatik (Berg) D.I
- BSA Bantam
- BYD D1
- Bavarian D I
- Char D1
- D (SEPTA Metro)
- D-1 (Sony)
- D-1 visa
- D-class Melbourne tram
- D1 (Longs Peak)
- D1 (building)
- D1 Grand Prix
- D1 Recordings
- D1 motorway (Czech Republic)
- D1 motorway (Slovakia)
- D1 multiple unit
- D1 road (Croatia)
- D1NZ
- DOCSIS
- Daimler D.I
- Decorah Bald Eagles
- Deutsche Flugzeug-Werke
- Dewoitine D.1
- Dhoom
- Di (disambiguation)
- Diablo (video game)
- Digital One
- Dopamine receptor D1
- Dunne D.1
- Euler D.I
- Flugzeugbau Friedrichshafen
- Fokker D.I
- Halberstadt D.II
- Hansa-Brandenburg D.I
- Haplogroup D1 (Y-DNA)
- Imperial and Royal Aviation Troops
- Iodothyronine deiodinase
- Junkers D.I
- Knoller D.I
- List of Dublin postal districts
- Mercedes D.I
- Min'an Electric D01
- Moscow Central Diameters
- NCAA Division I
- Nikon D1
- Northern Counties Committee
- Pennsylvania Railroad class D1
- Phönix D.I
- Proton (rocket family)
- Richter–Veresov Attack
- STS-61-A
- Schütte-Lanz D.I
- Siemens-Schuckert D.I
- T-Mobile International AG
- Town and country planning in the United Kingdom
- Vitamin D
- WKF D.I
- Yves (single)