Damper stacks, rotor blades, and turbomachines are provided. A rotor blade includes a main body including a shank and an airfoil extending radially outwardly from the shank. The rotor blade further includes a damping passage defined in the main body, the damping passage extending radially through the main body. The rotor blade further includes a damper stack disposed within the damping passage, the damper stack including a plurality of damper pins, each of the plurality of damper pins in contact with a neighboring damper pin.