The Hubble Space Telescope observed a spiral disk at the core of M 87 and derived a mass of 3 billion solar masses from the Keplerian velocity structure of the disk material. The gas disk is in the inset in the picture below. The picture also shows the central part of the galaxy with the jet of material shooting out perpendicular to the nucleus disk. GIF picture and text explanation. Here's a pointer to a plot of the data of large velocities in the disk and a text explanation.
Most galaxies are small.
Messier 32 is a dwarf elliptical companion of M 31 that is bright round blob just above M 31's disk in the picture above. It is a little closer to us than M 31 and probably has a 3 million solar mass black hole in its nucleus. It is slightly flattened so is of type E2. NGC 205 is another dwarf elliptical companion of M 31 and is below M 31's disk in the picture above. Leo I is a dwarf spheroidal in the constellation Leo.