William Valentine, FAIA, (born September 13, 1937, in Winston-Salem, North Carolina) is an American architect.

He worked at the firm HOK from 1962 to 2012, leading large projects such as the King Khalid International Airport and the Moscone Center.

In 1970, he moved to California to help open HOK's San Francisco office.

[3][4] Valentine has described his definition of good design as “a simple idea, elegantly executed and inspiring, with social significance and in harmony with the environment.”[5] He is a strong advocate for simplicity and efficiency and the "power of using less" as essential concepts of sustainable architecture,[6][7] and attributes his philosophy—that "all designs should be very simple….we should work to solve our clients' needs and to be helpful to the world"—to the influence of HOK co-founder Gyo Obata.

In 2009–2010, he led an HOK team that collaborated with The Weidt Group to create a market-rate, zero-emissions prototype design for a Class A commercial office building in St. Louis, Missouri.