William Holmes CBE (21 January 1873 – November 1961) was a British trade unionist and Labour Party politician. Holmes was born in Norfolk. His father was an active trade unionist, and his grandfather had been a Chartist. He left school at the age of 12 to become an agricultural labourer. He later took work at the Colman's mustard factory in Norwich and, in 1890, he joined the Norfolk and Norwich Amalgamated Labourers' Union. He was also a founder member of the Independent Labour Party, being particularly active in its cycling section. He was close to the Socialist League, although he did not join. In 1898, he did join the radical National Union of Gas Workers and General Labourers.