William Dartnell Johnson (9 October 1870 – 26 January 1948) was an Australian politician who was prominent in state politics in Western Australia for most of the first half of the 20th century.

[1] His father was George Groheim Johnson, a plumber, and his mother, Elizabeth Ann McCormish.

[1] He also helped establish the Kalgoorlie, Boulder and District Trades and Labor Council, and served as its secretary for two years.

[1] From 1901 to 1905, he served as the Labor MLA for the Electoral district of Kalgoorlie in the Western Australian Legislative Assembly.

[1] In the assembly, his proposal to build a railway line going North from Esperance, Western Australia rejected.

[1] Moreover, he lost his seat in the assembly to Joseph Davies (1866-1954) as a result of his opposition to the conscription of Western Australians in the First World War.