Smith Mountain Lake is a large artificial lake southeast of Roanoke, Virginia, and southwest of Lynchburg, Virginia. Initial proposals were made in the late 1920s to dam the Roanoke River and the Blackwater River at the Smith Mountain gorge to generate electricity. Construction on the dam began in 1960 and was completed in 1963. The lake reached its normal water level in March 1966. The lake is 20,600 acres (83 km²) and has over 500 miles (800 km) of shoreline. The north shore of the lake lies entirely in Bedford County. The majority of the south shore of the lake lies in Franklin County while a portion, including access to the dam, lies in Pittsylvania County.

The area lies in a broad valley nestled in the Blue Ridge Mountains of rural south-central Virginia of the Appalachian chain. Before the lake's creation, farming and logging were the primary industries. Communities around the lake include Moneta, Huddleston, Union Hall, White House, Penhook and Goodview. There is no post office with a Smith Mountain Lake mailing address. The Booker T. Washington National Monument is near the west end of the lake.

The dam produces pumped-storage hydroelectricity. Water flows through the dam turbines into Leesville Lake during the day (high demand time) to produce supplemental electricity. Water is then pumped from Leesville lake back into Smith Mountain Lake at night (low demand time). The dam is operated by Appalachian Power, part of American Electric Power.

The level of the lake varies during the day and night, as water flows through (and is pumped back through) the dam. The normal maximum level of the lake (also known as "Full Pond") is regulated to 795 feet (242 m) above sea level. The normal observed level (also known as "normal pond") is 794.20 feet (242.07 m). The level can be significantly lower during periods of extended drought. Lake levels were about six feet below normal from time to time, during the years 2001 to 2003, after five years of below-average rainfall.

Smith Mountain Lake has become a popular recreational area. Fishing is very popular, especially for striped bass. The lake has hosted professional fishing tournaments. Boating, water skiing, wakeboarding, and riding personal watercraft are also common activities. Smith Mountain Lake State Park opened in 1983 and provided a beach and a section for swimming. Golf at one of the several nearby courses is a popular landside activity.

The lake was featured prominently in the 1991 movie comedy What About Bob?, directed by Frank Oz and starring Bill Murray, Richard Dreyfuss and Julie Hagerty. It served as the stand-in for Lake Winnipesaukee in New Hampshire.