The United Self-Defense Forces of Colombia (Autodefensas Unidas de Colombia, or AUC, in Spanish) is an umbrella organization of regional illegal paramilitary groups in Colombia, each intending to protect different local economic, social and political interests by fighting insurgents in their areas. It is estimated that it has more than 20,000 militants. The AUC is considered to be a terrorist organization by many countries and organizations, including the United States and the European Union. The organization was formed in April 1997.

The AUC claimed its primary objective was to protect its sponsors and its supporters from insurgents and their activities, because the Colombian state had historically failed to do so. The AUC asserted itself as a regional and national counter-insurgency force. Former AUC leader Carlos Castaño Gil in 2000 claimed 70 percent of the AUC's operational costs were financed with cocaine-related earnings, the rest coming from "donations" from its sponsors.

Although, it is claimed the AUC demobilized in early 2006, there have been death threats issued by them since. One example of this was on May 8, 2008, when employees of a community radio station (Sarare FM Stereo) received a message stating : "For the wellbeing of you and your loved ones, do not meddle in subjects that do not concern the radio station. AUC, Arauca". A few days later the letters AUC were daubed on the front of their office. This threat was made due to their participation in a public meeting attended by members of a Congressional Human Rights Commission on the 27 September 2007. Here, members of the public denounced human rights abuses committed in Arauca Department by different parties to the armed conflict, including the AUC.