- Type: Commercial
- Abbreviation: OA
- Administration: President: David W. Thompson
- Founded: 2015
- Launchers: Antares | Minotaur | Pegasus
- Country: USA
Orbital ATK Inc. was an American aerospace manufacturer and defense industry company. It was formed in 2015 from the merger of Orbital Sciences Corporation and parts of Alliant Techsystems. Orbital ATK was purchased by Northrop Grumman in 2018.