Felix Constantijn Olivier Klos (3 March 1992) is a Dutch-American historian, political scientist, and politician of the Democrats 66 (D66).
Klos was educated at Lincoln College at the University of Oxford, and Middlebury College, Vermont. His academic work has focused on European integration. During his studies, he served as a Legislative Intern in the United States Senate, and as an International Office Intern for the Dutch social liberal party Demorcats 66.
In 2019, Klos was a candidate for D66 in the European Parliament elections. In the run-up to the elections he made a bid for delegation leader for D66, but was not elected. Sophie in 't Veld was chosen as delegation leader. He was a candidate for the party in the 2025 parliamentary election. D66's election victory secured his seat in parliament.
Klos is the author of Churchill on Europe: The Untold Story of Churchill's European Project (London, IB Tauris, June 2016) and Winston Churchill â Father of Europe (Amsterdam, 2016, Hollands Diep). The Guardian described the book as "scintillating" and observed that it "shows very persuasively how Churchill supported a postwar union of European states and wanted Britain to play a leading part in it.". In addition to the books Klos published a number of newspaper and magazine articles regarding Churchill's European legacy in the perspective of the UK EU referendum in June 2016.