Stanley David Griggs (September 7, 1939 – June 17, 1989) was a United States Navy officer and a NASA astronaut. He is credited with conducting the first unscheduled extra-vehicular activity of the space program during Space Shuttle mission STS-51-D. Griggs was killed when the vintage World War II-era training aircraft he was piloting – a North American AT-6D (registration N3931S) – crashed near Earle, Arkansas.