Fuel cell stacks may include a plurality of fuel cells including a membrane-electrode assembly that includes an anode electrode and a cathode electrode, gas diffusion layers respectively on opposing sides of the membrane-electrode assembly, a first separating plate having a first surface facing the anode electrode so as to be in contact with the gas diffusion layer and a second surface opposite to the first surface, and a second separating plate having a first surface facing the cathode electrode so as to be in contact with the gas diffusion layer and a second surface opposite to the first surface. At least one of the second surface of the first separating plate and the second surface of the second separating plate may include one or more protrusions protruding therefrom outwardly.