PSR J0952–0607 is a massive millisecond pulsar in a binary system, located between 3,200–5,700 light-years (970–1,740 pc) away from Earth in the constellation Sextans. It holds the record for being the most massive neutron star known as of 2022, with a mass 2.35±0.17 times as much as the Sun—potentially close to the Tolman–Oppenheimer–Volkoff mass upper limit for neutron stars. The pulsar rotates at a frequency of 707 Hz (1.41 ms period), making it the second-fastest-spinning pulsar known, and the fastest-spinning pulsar that is located in the Milky Way.