D20, D-20 or d20 may refer to:
Arts, entertainment, and media d20, a 20-sided die commonly used in role-playing games d20 System, a role-playing game system published by Wizards of the Coast Arriflex D-20, a film-style digital high definition movie camera D-20, a version of the Roland D-50 synthesizer Dimension 20, a tabletop role-playing game show made by CollegeHumor/Dropout Queen's Gambit Accepted, Encyclopaedia of Chess Openings code
Military 152 mm gun-howitzer D-20, a Soviet artillery piece , a destroyer that served with the Argentine Navy between 1961 and 1982 , a destroyer escort that served with the Brazilian Navy between 1944 and 1975 , a destroyer that served with the Royal Hellenic Navy between 1951 and 1972 , a Royal Navy guided missile destroyer launched in 1964 and decommissioned in 1987
Science D20, a diffractometer located at Institut Laue–Langevin used in neutron research Heavy water, or deuterium oxide (D2O or 2H2O)
Vehicles and transport D20 road (Croatia), a state road Aero Synergie Jodel D20, a French ultralight Chevrolet D-20, a pick-up truck made in Brazil and Argentina H Street Line, a Washington DC Metrobus route, designated D20 LNER D20, a class of British steam locomotives Senova D20, a subcompact car made by SAIC in China Soloviev D-20, a Soviet turbofan engine
Other Dublin 20, a Dublin, Ireland postal district 2020 Democratic National Convention, American political convention, branded as "D20"