Marion Susanne Michielsen (born 2 August 1985) is a Dutch bridge player. At the annual World Bridge Federation (WBF) meet in October 2014, she played on teams that won two world championships. Thus she became a World Women Grand Master.
In the European Bridge League championships of both 2004 and 2005, she played on both the under-21 (Schools) and the under-26 women (Girls) Dutch teams.
In world championship teams-of-four competition, Michielsen was a member of two 6-person teams that won quadrennial tournaments at Sanya, China in October 2014, namely the World Mixed Teams Championship (teams of male-female pairs) and the McConnell Cup (women teams). She played in partnerships with Zia Mahmood and Meike Wortel respectively.