Def Con Dos or DCD (Spanish for Def Con Two) is a metal rap band from Madrid, Spain.

Greatly influenced by hip hop bands Beastie Boys, Public Enemy, and Run D.M.C., and rock band Siniestro Total, they started rapping over hip hop bases created by producer Julián Hernández (musician and singer of Siniestro Total). In their Segundo Asalto tape (1989), the sound still was basically hip hop, but they started using rock guitars. Since Armas pal pueblo, the sound has been evolving into rap metal, with touches of techno and nu metal.

Texts in their lyrics and in the manifestos enclosed with their records are highly offensive and complex, with many references to pop culture: pop music, Spanish folklore, news, publicity, cinema, literature and Spanish and American comics. Armas pal pueblo (1994) was probably the first album made in Spain with a Spanish version of the Parental advisory: Explicit lyrics label on the cover.

Partly due to their polemical texts, DCD did not get much coverage from mainstream media in their beginnings, with the exception of some programs in Radio 3, a station belonging to the government-run Radiotelevisión Española. This situation changed when Basque film maker Álex de la Iglesia appointed them for the main themes in his films Acción mutante (Mutant Action, 1993) and El día de la bestia (Day of the Beast, 1995). Álex de la Iglesia also directed the videoclips for these songs.

They disbanded in 1999, but in 2004 announced the comeback of the band with all but one (Gautxito, one of the guitars) of the original members and released Recargando.

The current members of the band are César Strawberry (vocals), Samuel Barranco (vocals and producing), Sagan Ummo (vocals), Alberto Marín (guitars), Kiki Tornado (drums), and J. Al Ándalus (programming, producing and guitars).