William Rees-Thomas CB FRCP FRSM (15 June 1887 – 13 April 1978) was a Welsh psychiatrist.
[1] He was Medical Senior Commissioner for the Board of Control for Lunacy and Mental Deficiency.
Born in Senny, Breconshire, he was educated at County School, Brecon and Cardiff University.
During the First World War he served in the Royal Army Medical Corps[2] He was appointed to the Board of Control in 1931, replacing Arthur Rotherham as Medical Senior Commissioner[2] He was made a Companion of the Order of the Bath (CB) in 1950[3] He married Muriel Hodgson Jones in 1917; they had a son Frederick Douglas Rees-Thomas (1920–1995), and daughter Aelwyn Minette (1922–2012).
[5] In 1948 he remarried Ruth Darwin, a colleague of his on the Board of Control, daughter of Sir Horace and Lady Ida Darwin[6] they had no children, and she died in 1972.