Effective radii of GCs and EOs are plotted against their absolute V-magnitudes (black circles). The median effective radius per luminosity bin is given as squares. The six exceptionally bright GCs with luminosities between M_V =  −12.5 and  − 14.5 mag and effective radii below 4 pc are unconfirmed candidate clusters associated with NGC 4365 (Blom et al. 2012). The grey triangle shows the median effective radius, when these exceptionally bright compact GCs were removed in the bin at M_V =  −13.0 mag. In addition, early-type galaxies are shown as open circles. Highlighted are the two galaxy types compact ellipticals (cE) with their prototype example M 32, and the ultra faint dwarf galaxies (UFD) recently found in the Milky Way.