Frits Johan Marie Herman Koen (19 July 1876 – 11 February 1932) was a Dutch fencer and lieutenant of the infantry. As a military fencer he was a member of the "Koninklijke Officiers Schermbond". He represented the Netherlands at the 1906 Intercalated Games. Koen was engaged on 12 June 1900 in Padang to E. J. Maurer. They had a son in 1903. He died in Bogor, Dutch East Indies (now Indonesia), on 11 February 1932, aged 55.