John Frank Allen, FRS FRSE (May 5, 1908 – April 22, 2001) was a Canadian-born physicist. At the same time as Pyotr Leonidovich Kapitsa in Moscow, Don Misener and Allen independently discovered the superfluid phase of matter in 1937 using liquid helium in the Royal Society Mond Laboratory in Cambridge, England. Life Allen was born in Winnipeg; he was also known as Jack Allen. His father, Frank Allen, was a professor in physics at the University of Manitoba. John Allen studied physics initially at the University of Manitoba, where he received his bachelor's degree in 1928. Afterwards, he went to the University of Toronto to pursue postgraduate studies. He obtained his master's degree in 1930 and undertook his PhD working with John McLennan about superconductivity. He there developed and built his first cryostat which was taken by John McLennan for a demonstration of superconductivity in a public lecture to the Royal Institution in London. He obtained his PhD degree in 1933. With a two-year US National Research Council Fellowship which he obtained in 1933, he went to work as a postdoctoral researcher at Caltech between 1933 and 1935. In 1935, he joined the Mond Laboratory of the Royal Society in Cambridge to work with Pyotr Kapitsa on low temperature experiments. However, Kapitsa could not return from a visit of his mother in the Soviet Union in 1934 and never returned to Cambridge. So John Allen worked independently of Kapitsa on properties of helium at very low temperatures and published reports on the discovery of superfluidity in helium which were published side by side in Nature in January 1938. Despite the independent discovery at about the same time, the Nobel prize for Superfluidity was awarded only to Kapitsa in 1978. He stayed in Cambridge until 1947, when he took up an appointment as a professor in natural philosophy at the University of St Andrews, Scotland in 1947. In 1949, he was elected a Fellow of the Royal Society. During his tenure at the University of St Andrews, he was twice dean of the Faculty of Science, and oversaw the creation of a separate Faculty of Applied Science at Dundee as well as the development of the Science complex on the North Haugh in St Andrews, which opened in 1966. He was chair of the Very Low Temperature Commission of the International Union of Pure and Applied Physics from 1966 to 1969