Sir William Earle Welby-Gregory, 4th Baronet (4 January 1829 – 26 November 1898) was a British Conservative Party politician.
In 1863, William married Victoria Stuart-Wortley, by who he had three children.
He was elected as a Member of Parliament (MP) for Grantham at the 1857 general election, and held the seat until he resigned on 14 April 1868 (by taking the post of Steward of the Chiltern Hundreds) in order to contest a by-election for South Lincolnshire. He was elected unopposed South Lincolnshire on 29 April, and held the seat until he resigned again on 20 February 1884, this time by becoming Steward of the Manor of Northstead.