William Paxson Purcell III (born October 25, 1953) is an American politician who served as the fifth mayor[1] of the Metropolitan Government of Nashville and Davidson County, elected first in 1999 and reelected to a second term in 2003.

On June 24, 2008 he was named director of Harvard University's Institute of Politics (IOP) at the John F. Kennedy School of Government.

He attended Hamilton College in Clinton, New York where he served as Vice President of the Student Senate and was a columnist for the school newspaper.

As House Majority Leader and Chair of the Select Committee on Children and Youth, Purcell's work in the legislature positioned him in the forefront of education, health care, workers compensation, and criminal sentencing reforms.

Purcell and his wife Debbie Miller live in the historic Lockeland Springs neighborhood of East Nashville.