D3, D03, D.III, D III or D-3 may refer to:
Transportation
Roads
Aircraft
- Albatros D.III, a 1916 German biplane fighter aircraft
- Dewoitine D.3, a Dewoitine aircraft
- Dunne D.3, a British Dunne aircraft
- Fokker D.III, a 1916 German single-seat fighter aircraft
- Mercedes D.III, a 1914 German 6-cylinder, liquid-cooled inline aircraft engine
- Phönix D.III, a variant of the Austro-Hungarian First World War Phönix D.I biplane fighter
- Pfalz D.III, a 1917 German fighter aircraft
- Schütte-Lanz D.III, a 1918 German fighter aircraft prototype
- Siemens-Schuckert D.III, a 1917 German prototype single-seat fighter aircraft
Automobiles
Locomotives
Ships
Science and technology
Biology and medicine
Computing
- d3.js, Data Driven Documents, a JavaScript library for live web graphics based on changing data
- D3, a Pick database sold by Rocket Software
- DOCSIS 3, a cable modem standard
- D3, alternative name for AntiEXE, a boot sector virus
Entertainment
Video games
- Descent 3, a 1999 computer game
- Diablo III, a 2012 action role-playing game PC game by Blizzard Entertainment
- Dirt 3, a 2011 rallying video game
- ', a 2009 video game
- Disgaea 3, a 2008/2011 game in the Disgaea series
- Doom 3, a 2004 sci-fi horror first-person shooter computer game
- Driver 3, a 2004 racing, shooting, and adventure video game
Organizations
Other uses
See also