Arnold Machin O.B.E., R.A. (/ˈmeɪtʃɪn/; 30 September 1911 – 9 March 1999) was a British artist, sculptor, and coin and stamp designer.
Machin was born in Stoke-on-Trent in 1911. He started work at the age of 14 as an apprentice china painter at the Minton Pottery. During the Depression he learnt to sculpt at Stoke-on-Trent's Art School, which was opposite the Minton factory. In the 1930s he moved to Derby, where he worked at Royal Crown Derby and met his wife Patricia. He went on to study at the Royal College of Art in London.
After imprisonment in the Second World War as a conscientious objector, he returned to modelling and sculpture, and created many notable ceramics which are now prized collectors' items. In 1947 he was elected an associate member of the Royal Academy, was appointed a Master of Sculpture from 1959 to 1966 and became the longest-serving member of the Academy. He was elected an Academician in 1956 and a Fellow of the Royal Society of British Sculptors. From 1951 he was a tutor at the Royal College of Art.
In 1964 Machin was chosen to design a new effigy of the Queen for the decimal coinage, which was to be introduced from 1968. This effigy was used for all British coins until 1984. It was used on the coins of Canada from 1965 to 1989, Australia from 1966 to 1984 and New Zealand from 1967 to 1985.