Walter Charles Mills was born in Clonmel, County Tipperary, c. 1853. He married Helen Grey in Dublin in 1873, and they seem to have lived in Dublin from then on. They had six children between 1874 and 1890.
Mills had political cartoons published in the Weekly News in the 1880s, and in the Weekly Freeman and the Irish Weekly Independent in the 1890s and 1900s. He was on the Dublin staff of the Daily Graphic from 1893-1896, and the staff of the Irish Daily Independent from 1898 to 1900. In 1903 he worked as a special artist for the Graphic in Ireland.
From the 1910s on he contributed illustrations to Our Boys, in particular for "The Fourth Classical at St. Finbarr's", a long-running serial by John G. Rowe in which three boarding-school students during the War of Independence help the local I.R.A. track down a cache of arms and gold before the Black and Tans find it, which ran from 1919 to 1922. He died in South Dublin in the first quarter of 1931, aged 78.
- The 1901 census gives his age as 47, in the 1911 census he's apparently 60, and his age at death in 1931 is given as 78: based on those he could have been born any time from 1850 to 1853.
- Michael Flanagan, "True sons of Erin: Catholic/nationalist ideology and the politics of adventure in Our Boys 1914-32" (2006). Doctoral. Paper 9.
- Kayla Hertz, Irish political cartoons from Home Rule period acquired by Great Hunger Institute, Irish Central, 21 September 2014
- Joel A. Hollander, Coloured Political Lithographs as Irish Propaganda, The Edwin Mellen Press, 2007, pp. 50, 109, 136, 146-147, 165
- Simon Houfe, The Dictionary of 19th Century British Book Illustrators, Antique Collectors' Club, 1996, p. 232
- Collins Collection of Irish Political Cartoons, University of Illinois
- Bio at Scoop! (subscription required)