Williamson Mountain is a 6,304-foot peak in Oregon’s Cascade Range within the Deschutes National Forest and the Three Sisters Wilderness. Near the Lane-Deschutes county line and southwest of Mount Bachelor, it was named for Lt. Robert S. Williamson, who joined Lt. Philip Sheridan in the Pacific Railroad Surveys in central Oregon in 1855; the United States Board on Geographic Names approved the name in 1931. Earlier, it was called Leloo Mountain, a Chinook Jargon term meaning Wolf Mountain, derived from the French le loup. The Six Lakes Trail crosses the mountain, and Lava Lake Road passes nearby through this protected high-country landscape.