O'Neil Peak is a 5,758-foot-elevation (1,755-meter) mountain summit located in the Olympic Mountains, in Jefferson County of Washington state. It is situated in Olympic National Park and the Daniel J. Evans Wilderness. The nearest higher neighbor is Mount Duckabush, 1.6 mi (2.6 km) to the east-northeast, and O'Neil Pass lies 1.5-mile to the northeast. Precipitation runoff from the mountain drains into tributaries of the Quinault River. Topographic relief is significant as the summit rises over 4,300 feet (1,310 m) above the Quinault River in approximately 1.5-mile, and 2,700 feet above O'Neil Creek in one-half-mile.