Hans Willem Capel (3 June 1936 – 7 April 2023) was a Dutch theoretical physicist.
[1] He obtained his PhD in mathematics and physics at Leiden University in 1965 under Sybren Ruurds de Groot [de] with a dissertation titled: The hole-equivalence principle, the Van Vleck relation and the application to the theory of d-ions in Ligand fields.
[2][3] Capel subsequently became a lector of theoretical physics at the same university in 1970, and served as professor in the same field between 1979 and 1983.
[2] Capel is well known for introducing, in statistical physics, the Blume-Capel model, describing tricritical points.
[3] Capel was elected a member of the Royal Netherlands Academy of Arts and Sciences in 1990.