Lyon Peak is an 8,891-foot summit in California's Granite Chief Wilderness within Tahoe National Forest, in the northern Sierra Nevada. Set in a high alpine landscape west of the range crest, it stands between the headwaters of two branches of the American River, with runoff flowing north to the North Fork and south to the Middle Fork, making it part of a local divide. Though not exceptionally prominent by Sierra standards, it rises sharply above the Middle Fork nearby. The peak has long been a recognized named summit, appearing in publications by 1915, and is valued today for its protected mountain setting and place in the Sierra watershed.