Pelican Butte is a steep-sided shield volcano in the Cascade Range of southern Oregon. It is located 28 mi (45 km) due south of Crater Lake and 12 mi (19 km) northeast of Mount McLoughlin. Pelican Butte is the most prominent shield volcano in the southern Oregon Cascades and has a large volume at 4.8 cu mi (20 km³), making it one of the bigger Quaternary volcanoes in the region, approaching the size of some of the range's stratovolcanoes. While still part of the Cascades, Pelican Butte is disconnected from the main axis, forming above faults along the eastern border of the range. Pelican Butte is part of the Quaternary Mount McLoughlin Reach, a volcanic vent zone that runs from the volcano to Aspen Lake, encompassing 33 vents over an area of 357 sq mi (925 km²). Ice age glaciers carved a large cirque into the northeast flank of the mountain, but despite this erosion, its original shape is largely preserved. Several proposals have been made over the last few decades for the development of a ski area on this flank, with none implemented.

Dating for eruptive activity at Pelican Butte is unclear, ranging from less than 200,000 years ago to no more than 700,000 years ago. These eruptive episodes built a summit cone with tuff breccia and lapilli, later covered by lava flows before it was eroded. Eruptions began as explosive events and became thinner with ʻaʻā and block lava.

Pelican Butte is within the Fremont-Winema National Forest and forms part of the Sky Lakes Wilderness. A variety of flora and fauna live on and in the vicinity of the mountain. Named after nearby Pelican Bay at the north end of Upper Klamath Lake, Pelican Butte was also known by Native Americans as Mongina; the United States Coast and Geodetic Survey previously listed it under the name Lost Peak. Ancestral Native American groups related to the Klamath and Takelma people first hunted and gathered huckleberries in the area thousands of years ago. The Sky Lakes Wilderness area eventually became a popular location for white settlers to hunt, trap beaver and marten, and graze stock. A fire lookout tower is present on the summit of the volcano and is maintained by the United States Forest Service. A gravel road runs up to the summit of the mountain from Oregon Route 140.

Pelican Butte is located in Klamath County in southeastern Oregon near Fish Lake. It is about 28 mi (45 km) south of Crater Lake National Park and 12 mi (19 km) northeast of Mount McLoughlin. It is accessible from Oregon Highway 140. Located within the Fremont–Winema National Forest, Pelican Butte is part of the Sky Lakes Wilderness, which encompasses 113,849 acres (460.73 km²) of land in southern Oregon operated by the United States Forest Service. The wilderness area ranges in elevation from 3,800 to 9,495 feet (1,158 to 2,894 m).

While still part of the Cascade Range, Pelican Butte is disconnected from the main axis, having formed above a network of normal faults that mark the eastern border of the Cascades. The volcano reaches an elevation of 8,037 ft (2,450 m).^[a] Pelican Butte has steep sides, and despite erosion from glaciers, its original shape is mostly preserved. During the Pleistocene epoch (from circa 2.58 million to 11,700 years ago), glaciers formed a canyon and a cirque on the northeastern side of the volcano; they also reduced the summit elevation several tens of meters and carved out an intrusive conduit in the volcano. The volcano is no longer heavily glaciated.

Pelican Butte has a large volume at 4.8 cu mi (20 km³), making it one of the bigger Quaternary volcanoes in the region of Crater Lake and Mount Shasta. Its volume makes it one of the largest shield volcanoes in the Cascades, approaching the size of some of the range's stratovolcanoes. It is about 33 percent larger than Mount McLoughlin. Pelican Butte is the most prominent shield volcano in the southern Oregon Cascades.

On the volcano, at about 4,430 ft (1,350 m) elevation, Douglas fir and Ponderosa pine trees dominate. At an elevation of 5,410 ft (1,650 m), the Shasta red fir dominates certain areas; at elevations of 5,740 ft (1,750 m), the red fir as well as white fir become predominant. Close to the summit, endangered western white pine trees support populations of Clark's nutcrackers and gray jays. Mountain hemlock is also common at higher elevations, while lodgepole pines are more dominant around the Sky Lakes wilderness area's subalpine lakes; Engelmann spruce is also found sporadically. The understory of forest consists of huckleberry, snowbrush, heather, and manzanita.

Animals that live in the Sky Lakes Wilderness include elk in the summer to early fall, American martens, American black bears, cougars, coyotes, pikas, golden-mantled ground squirrels, and ospreys. In a study of relationships between the northern spotted owl and its prey species, scientists identified animals including the northern flying squirrel, Bushy-tailed woodrat, and voles as living at Pelican Butte. Less common prey animals included deer mice and Townsend's chipmunk as well as insects. American bald eagles also live on the mountain. Some of the lakes in the area are stocked with game fish. Klamath Lake near Pelican Butte is home to sucker fish, including the Klamath largescale sucker, the Klamath smallscale sucker, and the endangered Lost River sucker and shortnose sucker.