| William Lambert | |
| Nationality: | Australian |
| Order: | 52nd Lord Mayor of Sydney |
| Term Start1: | 1921 |
| Term End1: | 1921 |
| Predecessor1: | William Patrick Fitzgerald |
| Successor1: | William Percy McElhone |
| Constituency Mp2: | West Sydney |
| Parliament2: | Australian |
| Predecessor2: | T. J. Ryan |
| Successor2: | Jack Beasley |
| Term Start2: | 3 September 1921 |
| Term End2: | 6 September 1928 |
| Birth Date: | 24 March 1881 |
| Birth Place: | Swallow Creek, Australia |
| Death Place: | Randwick, New South Wales, Australia |
William Henry Lambert (24 March 1881 – 6 September 1928) was an Australian politician and unionist, serving for one term as Lord Mayor of Sydney in 1921.
Lambert was born at Swallow Creek, near Orange, on 24 March 1881 to Irish-born stonemason James Lambert and Elizabeth, née O'Brien. He received a primary education and subsequently worked as a shearer. He soon became involved with the Australian Workers' Union. On 9 October 1909 he married waitress Bertha Anne McConnell at Dubbo, Dubbo. In 1915 he became secretary of the AWU's central branch.
Lambert was active in the anti-conscription movement during World War I. He was elected to Sydney Municipal Council in December 1918 and was Lord Mayor of Sydney in 1921. He used his casting vote to support Labor policy, and was noted for preferring the Australian flag to the Union Jack.
Lambert was elected to the Australian House of Representatives for the seat of West Sydney in the 1921 by-election following the death of T. J. Ryan, representing the Australian Labor Party. He kept a fairly low profile in Parliament, but became intimately involved in faction politics. His political fortunes declined after Jack Lang became leader of the New South Wales Labor Party. As such, he lost pre-selection for West Sydney in 1928.
Lambert told the Daily Telegraph Pictorial that he had been offered £8000 in 1925 to resign his seat in favour of Ted Theodore. Lambert had denied this when it appeared in the Evening News in 1925, but the Bruce government nevertheless appointed a royal commissioner, who discounted Lambert's testimony but found that William Mahony had been compensated in such a way.
Lambert died on 6 September 1928 of heart disease.