Donald Jason Cothern (born November 12, 1970) is a brigadier general in the United States Space Force currently serving as the deputy commander of the Space Systems Command. He transferred to the Space Force from the United States Air Force in May 2021. Prior to his current assignment, he was the assistant program director for development at the F-35 Lighting II Joint Program Office, where he was responsible for F-35 fighter fifth generation modernization activities.