Blackwater Worldwide, formerly Blackwater USA, is a self-described private military company founded in 1997 by Erik Prince and Al Clark. It has alternatively been referred to as a security contractor or a mercenary organization by numerous reports in the international media. Blackwater is based in the U.S. state of North Carolina, where it operates a tactical training facility that it claims is the world's largest. The company trains more than 40,000 people a year, from U.S. or foreign military and police services, as well as other U.S. government agencies. The training consists of military offensive and defensive operations, as well as smaller scale personnel security. Technologies used and techniques trained are not limited by U.S. domestic law, although it is unclear what legal status Blackwater operates under in the U.S. and other countries, or what protection the U.S. extends to Blackwater operations globally.

Blackwater is currently the largest of the U.S. State Department's three private security contractors, providing a total of 987 contractors. Of the 987 provided, 744 are U.S. citizens. At least 90 percent of its revenue comes from government contracts, two-thirds of which are no-bid contracts.

On March 31, 2004, four Blackwater Security Consulting (BSC) employees were ambushed and killed in Fallujah, and their bodies were hung on a bridge to cheering Iraqi crowds. In a response to this, U.S. forces attacked the city of Fallujah.

On September 16, 2007, Blackwater employees in Nisour Square, Baghdad shot and killed 17 Iraqi civilians, at least 14 of whom were killed "without cause" according to the Federal Bureau of Investigation.

Blackwater Worldwide is currently contracted by the United States government to provide security services in the Iraq War. Blackwater Worldwide Oversight records. In October 2007, Blackwater USA rebranded themselves as Blackwater Worldwide.