William Gustavus Whiteley (August 7, 1819 – April 23, 1886) was an American lawyer and politician from Wilmington, in New Castle County, Delaware.

[1]: 983–4 William attended Bullock's School at Wilmington and graduated from Princeton College in 1838.

He studied law under James A. Bayard Jr., was admitted to the Delaware Bar in 1841, and began a practice in Wilmington.

Whiteley was mayor of Wilmington from 1875 to 1878 and was a member of a commission to settle fishery disputes between New Jersey and Delaware in 1877.

Whiteley died at Wilmington and is buried in the Old Broad Street Presbyterian Church Cemetery at Bridgeton, New Jersey.