William Klesse is Chairman of the Board, CEO and President of Valero. He was elected Chairman of the Board in 2007, and its President a year later. Other executive positions he has held at the company include: Vice Chairman of the Board; Executive VP; COO and Executive VP of Refining and Commercial Operations since he acquired Ultramar Diamond Shamrock Corporation (UDS) in 2001. He boasts over four decades of experience in practically every aspect of the refining industry, including more than 20 years of service with UDS and Valero.