Johanna "Jopie" Katarina Selbach (27 July 1918 – 30 April 1998) was a freestyle swimmer from the Netherlands. She won gold medals at the 1934 European Aquatics Championships (with Willy den Ouden, Rie Mastenbroek and Ans Timmermans) and 1936 Summer Olympics (with den Ouden, Mastenbroek and Tini Wagner) in the women's 4 × 100 m freestyle relay.^[1]