Supermassive black holes are thought to exist in the centres of most massive galaxies and their masses have been found to correlate strongly with the properties of their host galaxies like overall luminosity or central velocity dispersion. Yet it is unknown what processes have established these correlations and if and how they continue towards lower mass systems. In my talk I will present results from our search for massive black holes in ultra-compact dwarf galaxies and in massive globular clusters of the Milky Way.