David Thomas (16 July 1880 – 27 June 1967) was a Welsh educationalist, Welsh language writer and Labour Party pioneer in Wales.
Born in Llanfechain, Montgomeryshire, he taught mainly in Wales, initially as a non-certificated teacher, but he obtained a teacher's certificate in 1905.
Thomas was active in the Labour Party and labour movement in North Wales.
His first book, Y Werin a'i Theyrnas (The People and Their Kingdom, 1910), was influential on trade unionists and Welsh Labour members.