Spearfish
- Country: United States
- State: South Dakota
- Population: 11,531 (2016)
- Latitude: 44° 29.4' N (44.49082°)
- Longitude: 103° 51.6' W (-103.85937°)
- Elevation: 1,112 m/3,647 ft. above sea level
- Time zone: America/Denver (UTC -07:00); DST observed (UTC -06:00)