These are the names I have found so far. If you know of any others please get in touch with me. Thank you.
Joseph Marius Jean Avy (1871 - 1939) - French Croix de Guerre – French artist
Geoffrey de Gruchy Barkas, MC, artist/film maker
Hans Bartle (1880 - 1943) - Austrian official WW1 artist. Iron Cross; Silver Medal for Bravery; the Knight's Cross of the Franz Joseph Order
Alan Edmund Beeton, MC
John Warwick Brooke DCM – official WW1 war photographer
John Cosmo Clark, MC (1897 – 1967) – British artist and art teacher; served in Artists Rifles WW1
Philip Lindsey Clark, DSO, ARBS (1889–1977) - British sculptor. In December 1917, he was awarded the Distinguished Service Order (D.S.O) for "...conspicuous gallantry and devotion to duty when in command of the left flank company of the battalion."
Helena Gleichen OBE, DStJ (1873 – 1947) – artist. For her First World War work, Helena was awarded the Italian Bronze Medal of Military Valour and was invested as a Dame of Grace of the Order of St John of Jerusalem and as an OBE in 1920.
William Robert Gregory MC (1881 – 1918) - Irish-born, RFC/RAF British airman, artist and cricketer; France made him a Chevalier of the Legion d'Honneur in 1917
Antony Gibbons Grinling, MC – artist and sculptor
Carl W Herman, MM (1888 – 1955) – artist
Christopher Wyndham Hughes MC (1881-1961) - artist; served as Temporary Captain in the 7th Battalion Wiltshire Regiment
Charles Sargeant Jagger MC ARA (1885 – 1934) British sculptor
Richard Barrett Talbot Kelly MC (1896-1971), Lieutenant Royal Field Artillery
Paul Maximilien Landowski, Croix de Guerre (1 June 1875 – 31 March 1961) – French Scultpor and WW1 camouflage artist
A W Lloyd, MC – Arthur Wynell Lloyd (1883 - 1933) – British cartoonist
Walter Marsden MC (1882–1969) – sculptor
John B. McDowell, MC, BEM (1877 – 1954) – British film maker, director and cameraman during WW1
Waldo Peirce (December 17, 1884 – March 8, 1970) - an American painter, who for many years revelled in living the life of a bohemian expatriate. Awarded the Croix de Guerre
William Charles Penn MC (1877 – 1968) - artist; 5th Battalion The King’s (Liverpool) Regiment
Geneste Penrose MM (1889 – 1974) – artist
Gerald Spencer Pryse MC (1882–1956) - British artist and lithographer.
E. Claude Rowberry, MM, (1896 - 1962) – artist
E.H. Shepard, MC (1879 – 1976) – artist (illustrator of A.A. Milne’s “Pooh” stories
William George Storm, MC (1882 - 1917) – Canadian artist
Dents Wells, BEM (1881-1973) served in the Artists Rifles during WWI; awarded a B.E.M. for gallantry. https://en.wikipedia.org/wiki/British_Empire_Medal
Charles Arthur Wheeler, DCM (1880 - 1877) - New Zealand artist. Served in 22 Bn Royal Fusiliers; awarded the Distinguished Conduct Medal (1916) for his actions at Vimy Ridge
Sir George Hubert Wilkins MC & Bar (31 October 1888 – 30 November 1958).