William Alexander Lester III (born February 6, 1961) is an American former professional racing driver who last competed in the Grand Touring category in the Rolex Sports Car Series for Autohaus Motorsports. In 1984, he earned a Bachelor of Science degree in EECS from the University of California, Berkeley. Fresh out of college, he worked at Hewlett-Packard for a few years before deciding he wanted to focus on auto racing.

Until 2007, he competed full-time in the NASCAR Craftsman Truck Series, being at the time the only African-American competing full-time in a NASCAR circuit. He also participated in a number of Nextel Cup Series races. From 2008–2010, he competed in the Daytona Prototype category in the Rolex Sports Car Series.

He currently works as a member of the National Motorsports Appeals Panel.

He began racing in the road course circuits, running in the SCCA and IMSA series. He made his IMSA debut in 1989 at Sears Point International Raceway, qualifying ninth and finishing 12th in a Chevrolet Camaro. He also picked up a victory that year in an endurance race at Sears Point. In 1990, he began running the SCCA, running an unsponsored Oldsmobile Cutlass for Rocketsports at Portland, and one race for Tom Gloy at Mid-Ohio. He did not race professionally again until 1996, running SCCA events at Watkins Glen, Elkhart Lake, Wisconsin, Sears Point, and Reno, Nevada. He competed in the 24 Hours of Daytona in 1998 and 1999, finishing fifth and tenth, respectively.