William James Bull (29 September 1863 – 23 January 1931), knighted in 1905 and known as Sir William Bull, 1st Baronet from 1922, was a solicitor and Conservative Party politician in the Hammersmith area.
Born in Hereford, he was the son of a London-based solicitor. Following his father's death at the age of 14 he entered the family law firm of Bull and Bull. He was admitted as a solicitor in 1889 and became a partner in the practice.
In 1900 he was elected to the House of Commons as Conservative member of parliament for Hammersmith. When the constituency was abolished in 1918 he became MP for the new seat of Hammersmith South, retiring from parliament at the 1929 general election due to ill health. From 1903-1921 he was private parliamentary secretary to Lord Long of Wraxall, who held various cabinet posts over that time. In parliament he also argued the case for the construction of the Channel Tunnel.
He died suddenly, collapsing after giving the toast at a dinner in Somerset, at the age of 67.
- "Sir William Bull. Thirty Years An M.P.". The Times: p. 14. 24 January 1931.