We demonstrate that black holes likely have an energy or mass gap, E_g/c^2=m_g, that is of the order m_g = m_p^2/M_BH. Interestingly, the mass of the black hole divided by the mass gap seems closely related to the Bekenstein-Hawking entropy and thereby potentially leads to a quantization of black holes. Even if mathematically trivial, this could be a potentially important step toward better understanding the potential to quantize black holes. Our focus is mainly on Schwarzschild black holes, but we also briefly discuss Reissner-Nordström black holes. It is also important that this results in minimal gravitational acceleration, creating a gravitational gap that could potentially eliminate dark matter.