# D1

D1, D01, D.I, D.1 or D-1 can refer to:

## Science and technology
### Biochemistry and medicine

* ATC code D01 Antifungals for dermatological use, a subgroup of the Anatomical Therapeutic Chemical Classification System
* Dopamine receptor D$_1$, a protein
* Haplogroup D1 (Y-DNA)
* Vitamin D$_1$, a form of Vitamin D
* DI, Iodothyronine deiodinase type I, an enzyme involved with thyroid hormones

### Technology

* Nikon D1, a digital single-lens reflex camera
* D1, former brand of T-Mobile in Germany
* D1, an abbreviation for DOCSIS 1.0 1.0, an international telecommunications standard
* D-1 (Sony), an early digital video recording format
* STS-61-A, also known as D-1, the 22nd mission of NASA's Space Shuttle program
* D-1, from the Proton (rocket family), Russian rockets
* Mercedes D.I, a 1913 German aircraft engine

## Military
### World War I fighter aircraft

* AEG D.I
* Albatros D.I
* Halberstadt D.I, experimental version of Halberstadt D.II (and Aviatik D.I variant)
* Aviatik (Berg) D.I
* Daimler D.I
* Deutsche Flugzeug-Werke D.I
* Euler D.I
* Flugzeugbau Friedrichshafen D.I
* Fokker D.I
* Hansa-Brandenburg D.I
* Junkers D.I
* Knoller D.I, an Imperial and Royal Aviation Troops aircraft
* Phönix D.I
* Schütte-Lanz D.I
* Siemens-Schuckert D.I
* WKF D.I, an Imperial and Royal Aviation Troops aircraft

### Other uses in military

* Char D1, a 1930s French tank
* Dewoitine D.1, a 1920s French single-seat fighter aircraft
* Dunne D.1, a 1907 British experimental aircraft
* 152 mm howitzer M1943 (D-1), a Soviet World War II artillery system
* HMS D1, British early 20th century submarine
* USS D-1 (SS-17), a 1909 American submarine

## Transportation
### Locomotives and trams

* D1-class, a variant of D-class Melbourne tram
* D1 multiple unit, a train built in 1960s-1980s in Hungary for Soviet railways
* LB&SCR D1 class, an 1873 British tank locomotive
* NCC Class D1, a Northern Counties Committee Irish gauge steam locomotive
* Pennsylvania Railroad class D1, an 1868 American steam locomotive
* Bavarian D I, an 1871 Bavarian tank locomotive
* Min'an Electric D01, a sports luxury vehicle

### Roads

* D1 road (Croatia)
* D1 motorway (Czech Republic)
* D1 motorway (Slovakia)

### Other uses in transportation

* D1, a model of BSA Bantam British motorcycle
* D1, a commuter rail line of Moscow Central Diameters
* D1 Denby Darts, a bus service in Yorkshire, UK
* BYD D1, an electric multi purpose vehicle (MPV)

## Sports

* NCAA Division I, D-I, the highest division of American collegiate athletics
* D1 Grand Prix, a production car drifting series from Japan
* D1NZ, a production car drifting series in New Zealand

## Other uses

* D1 (building), a residential building in Dubai
* D1 (Longs Peak), a technical climbing route in Colorado, U.S.
* D1, a Dublin postal district
* D1, a guitar model by C. F. Martin & Company
* D1, a code in Town and country planning in the United Kingdom
* D1, a transmitter equipped juvenile female bald eagle from the 2011 clutch of the Decorah Bald Eagles
* D1, a discount store chain from Colombia.
* D-1 visa, a non-immigrant U.S. visa
* "D-1", a song from Yves (single) by Loona
* D1 Recordings, an Irish independent techno record label
* D01, ECO code for the Richter-Veresov Attack chess opening
* Digital One - also known as D1 National, a digital radio multiplex in the United Kingdom
* Dhoom, a 2004 Indian Hindi-language action film by Sanjay Gadhvi, first part of the Dhoom film series
* Diablo, a 1997 action role-playing video game by Blizzard Entertainment