Mount Bachelor, Dormant stratovolcano in Deschutes County, Oregon, US.

Mount Bachelor is a dormant stratovolcano in Deschutes County, Oregon, rising to an elevation of 9,065 feet (2,763 meters). The summit displays a broad, rounded shape and the slopes consist of dark rock layers of volcanic origin.

A shield volcano formed on the site between 15,000 and 11,000 years ago; the larger stratovolcano above it was built later, between 18,000 and 8,000 years ago, from basalt and basaltic andesite. The last eruption occurred 8,000 to 10,000 years ago. Less than 7,000 years ago the Mount Mazama eruption blanketed the peak in ash.

The name Bachelor refers to the peak standing apart from the Three Sisters; it was called Bachelor Butte until the 1980s, and long before that Brother Jonathan. In 1981 the mountain served as a stand-in for Mount St. Helens in the film "Mount St. Helens".

The access road Cascade Lakes Highway runs in summer to the parking area below the summit and provides trailheads for hikes. In winter, access is only through the ski runs and lifts, with upper areas often exposed to strong winds.

The summit has no crater: clustered vents trending northwest–southeast fed block lava flows of basalt and andesite, with little tephra found nearby. The Mount Bachelor Observatory also operates at the top. The climbing trail crosses the volcano's own lava on the way up.