Harold Robert Millar was born in Morton, Dumfries, Scotland, on 6 February 1869. His father was an officer of the Inland Revenue. He pursued a career in civil engineering before settling on art, studying at the Wolverhampton Art School and the Birmingham School of Art. He became an illustrator and cartoonist, drawing for magazines including Punch, Good Words and The Strand, and illustrating books including a series of fairy tale anthologies and novels and children's books by Robert Louis Stevenson, Rudyard Kipling and E. Nesbit among others. He also worked in comics, drawing "Jungle Land" (1919) for The Sunday Fairy. He died in Surrey in the fourth quarter of 1942.
- Alan Clark, Dictionary of British Comic Artists, Writers and Editors, The British Library, 1998, p. 112
- Simon Houfe, The Dictionary of 19th Century British Book Illustrators, Antique Collectors' Club, 1996, pp. 230-232