Grassy Knob Wilderness, Protected wilderness area in Rogue River-Siskiyou National Forest, Oregon.

Grassy Knob Wilderness is a 17,200-acre protected area in the Klamath Mountains of southwestern Oregon, within the Rogue River-Siskiyou National Forest. Elevations range from near sea level to 2,342 feet at the summit of Grassy Knob. Dry Creek, a tributary of the Sixes River, marks the northern boundary, while the Elk River, with Wild and Scenic designation, forms the southern border. The terrain includes steep slopes, ravines, and small waterfalls.

Grassy Knob Wilderness was designated by the United States Congress in 1984 and now covers 17,200 acres (6,961 ha) in the Klamath Mountains of southwestern Oregon, within the Rogue River-Siskiyou National Forest. Like most wilderness areas in Oregon, it is managed by the Forest Service.

The name Grassy Knob comes from the open grassy summit of the knob itself, a clearing in otherwise forested terrain. The area is managed by the Forest Service, and its few routes are largely user-made paths rather than constructed trails. Visitors today mostly fish, watch wildlife and hike, with solitude as the main draw.

This area has no developed trails and requires visitors to have advanced navigation skills with map and compass. All motorized equipment is prohibited, so you must travel on foot with a backpack.

The Elk River, which forms the southern boundary, carries a Wild and Scenic designation, and some claim it is the most productive salmon stream of its size outside Alaska. The northern boundary is marked by Dry Creek, a tributary of the Sixes River.