Mons Gruithuisen Gamma (γ) is a lunar dome that lies to the north of the Gruithuisen crater at the western edge of the Mare Imbrium. It is located at selenographic coordinates 36.6° N, 40.5° W. This formation is named after nearby Gruithuisen crater.

This massif is shaped as a rounded dome in the surface, occupying a diameter of 20 km and climbing gently to a height of 900 meters. At the crest is a small craterlet. This formation appears foreshortened when viewed from the Earth, and it has been described as resembling an "upturned bathtub".