Galen is a small lunar impact crater that lies in the rugged region between the Montes Apenninus range to the west and the Montes Haemus in the east. It is located to the south-southeast of the crater Aratus, a slightly larger formation. Further to the west is the crater Conon, near the flanks of the Montes Apeninnus. Galen was previously designated Aratus A before being given a name by the IAU.