Constellis, formerly Blackwater, is an American private military contractor founded on December 26, 1997, by former Navy SEAL officer Erik Prince. It was renamed Xe Services in 2009, and was again renamed to Academi in 2011, after it was acquired by a group of private investors. In 2014, Academi merged with Triple Canopy to form Constellis Holdings.

Constellis and its predecessors provide contract security services to the United States federal government. Since 2003, it has provided services to the Central Intelligence Agency.

In 2007, Blackwater received widespread notoriety for the Nisour Square massacre in Baghdad, when a group of its employees killed 17 Iraqi civilians and injured 20. Four employees were convicted in the United States and were later pardoned on December 22, 2020, by President Donald Trump.

Blackwater USA was formed on December 26, 1996, by Al Clark and Erik Prince in North Carolina, to provide training support to military and law enforcement organizations. In explaining its purpose, Prince stated: "We are trying to do for the national security apparatus what FedEx did for the Postal Service."

Prince purchased approximately 7,000 acres (28 km²) of the Great Dismal Swamp, a vast swamp on the North Carolina–Virginia border that is now mostly a national wildlife refuge. "We needed 3,000 acres to make it safe," Prince told reporter Robert Young Pelton. There he created his private training facility and his contracting company, Blackwater, which he named for the peat-colored water of the swamp.

The Blackwater Lodge and Training Center officially opened on May 15, 1998, with a 6,000-acre (2,400 ha), $6.5 million facility headed by Robert Anderson. It comprises several ranges: indoor, outdoor, urban reproductions; an artificial lake; and a driving track in Camden and Currituck counties. The company says it is the largest training facility in the country. The concept was not a financial success but was kept solvent by sales from sister company Blackwater Target Systems.

Jeremy Scahill has claimed that Blackwater Security Company (BSC) was the brainchild of Jamie Smith, a former CIA officer who became vice president of Blackwater USA and the founding director of Blackwater Security Company, holding both positions simultaneously. However, this claim is denied by Prince and Blackwater executive Gary Jackson, who describe firing Smith from his position as a low-level administrator for "non-performance" after a thirty-day contract. Smith has been accused of further embellishing his military and contracting record to defraud investors at SCG International Risk.

BSC's first assignment was to provide twenty men with top-secret clearance to protect the CIA headquarters and another base that was responsible for hunting Osama bin Laden. Blackwater was one of several private security firms employed following the U.S. invasion of Afghanistan. BSC was originally formed as a Delaware LLC and was one of over sixty private security firms employed during the Iraq War to guard officials and installations, train Iraq's new army and police, and provide other support for coalition forces.