Mount Andrus (75°48′0″S 132°18′0″W / 75.80000°S 132.30000°W / -75.80000; -132.30000 (Mount Andrus)) is a peak 2 nautical miles (3.7 km; 2.3 mi) southeast of Mount Boennighausen in the southeast extremity of the Ames Range, in Marie Byrd Land, Antarctica.

Mount Andrus was mapped by the United States Geological Survey (USGS) from surveys and United States Navy air photographs, 1964–68. It was named by the United States Advisory Committee on Antarctic Names (US-ACAN) for Lt. Carl H. Andrus, United States Navy, medical officer and Officer-in-Charge of Byrd Station in 1964.

Mount Andrus is the youngest of the shield volcanoes in the Ames Range, which formed during the Miocene. Late-stage volcanic activity resumed at Mount Andrus in the late Pleistocene or the Holocene. Its has a 4.5 kilometres (2.8 mi) wide caldera at its summit. While the age of Mt. Andrus is not well known it is one of the oldest trachytic shield volcanoes in Marie Byrd Land, similar in age to Mount Hampton. The westward face of the mountain is drained by the Coleman Glacier, with significant crevassing present.