William Holmes (1873–November 1961), usually known as Bill Holmes, 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 twelve 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.
In 1905, Holmes was elected to Norwich City Council, becoming a Labour Party councillor when that organisation was established the following year. Also in 1906, he worked with George Edwards to found the National Union of Agricultural Workers (NUAW). Five years later, he was elected to the union's executive.
Holmes became prominent in the Labour Party and was appointed as one of its first two National Organisers in 1913. He stood unsuccessfully for the party in the Horncastle by-election, 1920 and in Stafford at the 1923 UK general election. He continued in the post even though that year he was elected as President of the NUAW, but stood down in 1928 to become the union's General Secretary.