Ulven concentration camp (Norwegian: Ulven fangeleir; Ulven means "the wolf") was a concentration camp in the municipality of Os in Hordaland county, Norway. It was located just outside the village of Osøyro. It was established in June 1940 during the Nazi administration of occupied Norway, and it was the first of its kind in Norway. It was designated a Polizeihäftlingslager, under the administration of the Nazi "Security Police" (SIPO).
Initially, prisoners were Jewish or Communist, but a broader array of members from prosecuted groups began arriving at the camp. Conditions were relatively benign until 1942, when Untersturmführer Otmar Holenia, nicknamed "the Storm", took command and imposed harsher conditions.
Ulven was used for purposes of executing individuals for various reasons. It is not known how many were murdered in the camp.
In the course of the summer of 1943, all prisoners at Ulven were transferred to the nearby Espeland concentration camp.