Some embodiments relate to a rotor blade of a wind turbine, a wind turbine having a rotor blade and a method for optimizing a rotor blade. Some embodiments relate to a rotor blade of a wind turbine, wherein the rotor blade has a leading edge, a trailing edge, a suction side and a pressure side, and extends in a longitudinal direction of a rotor blade between a root end and a tip end, wherein a direct connection between the leading edge and the trailing edge is termed the chord line and the length thereof is termed the chord length, wherein the rotor blade has at least one airfoil element, wherein the at least one airfoil element is arranged at the trailing edge with a proximal portion adjoining a trailing edge region and projects from the trailing edge with a distal portion having a projecting direction, which is oriented substantially parallel to the direction of the chord length, wherein the at least one airfoil element has an airfoil element thickness in a direction perpendicular to the projecting direction, wherein the at least one airfoil element has a pressure side airfoil side facing the pressure side and a suction side airfoil side facing the suction side, wherein the at least one airfoil element has a cross-section substantially orthogonal to the projecting direction, characterized in that the cross-section of the at least one airfoil element has at least one local minimum of the airfoil element thickness, wherein the airfoil element thickness in the cross-section on both sides of the local minimum has a larger value.