The Elk River is a tributary of the Kanawha River, 172 miles (277 km) long,^[5] in central West Virginia in the United States. Via the Kanawha and Ohio rivers, it is part of the watershed of the Mississippi River.

The Elk is formed in the Allegheny Mountains in Pocahontas County by the confluence of two short streams, the Big Spring Fork and the Old Field Fork, which join near the community of Slatyfork. It flows above ground for several miles before it sinks into a network of caverns and flows underground for more than five miles. The old riverbed of solid rock, however, remains above ground in this section known as "The Dries." It follows a generally westward course across the unglaciated Allegheny Plateau, through Randolph, Webster, Braxton, Clay, and Kanawha Counties, past the towns of Webster Springs, Sutton, Gassaway, Clay, Clendenin, and Elkview before joining the Kanawha River at Charleston.

At Sutton, a U.S. Army Corps of Engineers concrete dam causes the Elk to form Sutton Lake.

The Elk's largest tributaries are the Holly River and the Birch River, both of which join it in Braxton County.

The upper portion of the river, above Sutton Lake, is a popular coldwater trout stream. Some reports of a 2013 Wake Forest University study of selenium contamination in Sutton Lake in North Carolina (allegedly due to coal ash from the Sutton power plant of Duke Energy). erroneously attributed this contamination to Sutton Lake in West Virginia.^[7] Sutton Lake in North Carolina is on the Cape Fear River; whereas Sutton Lake in West Virginia is on the Elk River, an entirely different river drainage basin. ^{[8] [9]}

Below Sutton Lake, is a high-gradient warmwater fishery well known for its muskellunge, walleye and smallmouth bass fishing. The Elk River serves as the source of water for 1500 miles of pipeline that carry its water to customers in central and southwestern West Virginia.^[10]

The river's name most likely comes from the Native Americans of the area, who saw great numbers of elk near the stream.^[11]

According to the Geographic Names Information System, the Elk River has also been known historically as:

• Pe-quo-ni
• Pe-quo-ni-cepe
• Pequoni
• Tis-chil-waugh
• Tiskelewah
• Tiskelwah
• To-que-man
• To-qui-min-cepe

• Kanawha River
• List of West Virginia rivers