M87 is one of the most luminous nearby galaxies and hosts one of the most massive black holes known, making it a very important target for extragalactic studies. The supermassive black hole has been the subject of several stellar and gas dynamical mass measurements; however, the best current stellar dynamical black hole mass is larger than the gas dynamical determination by a factor of two, corresponding to a 2-sigma discrepancy. In this talk, I will review the gas dynamical black hole mass measurements that have been made over the years for M87, focusing in particular on the most recent measurement from multi-slit Space Telescope Imaging Spectrograph observations from the Hubble Space Telescope. I will also discuss the strengths and weaknesses generally associated with stellar and gas dynamical black hole mass measurement methods, and the current state of cross-checks between the two methods that have been carried out within the same galaxy.
