The Lonesome Bachelor is a summit in Ravalli County, Montana, United States.
The Lonesome Bachelor is part of the Bitterroot Range which is a subrange of the Rocky Mountains. With an elevation of , The Lonesome Bachelor is the 860th-highest summit in the state of Montana. It is located in the SelwayâÂÂBitterroot Wilderness on land managed by Bitterroot National Forest. The nearest community is Darby, to the east, and the nearest higher neighbor is Como Peaks, to the east. Precipitation runoff from the mountain's slopes drains to the Bitterroot River. Topographic relief is significant as the summit rises approximately above headwaters of Little Rock Creek in . This mountain's toponym has been officially adopted by the United States Board on Geographic Names.