Recent observational and theoretical work suggest that black holes are essential components of galaxies. In fact, they may be one of the keys to understanding how galaxies form and evolve. I will give a general overview of the observational results for black holes in galaxies, including discussion of their effects on the stellar orbital distribution. I will focus the talk on the two extreme mass ranges, from whether globular clusters contain black holes up to black holes in brightest cluster galaxies. The present results suggests that the black hole correlations span over seven orders of mass. This concordance suggests a more intimate connection between these different types of systems than what has previously been thought. I will also discuss the future of black hole studies, from space and from the ground.