H-R diagram of all the spectroscopically confirmed hot luminous stars in the MEDUSA region a) and R136 region b). W-R stars (red squares), Of/WN stars (cyan triangles), O-type stars (yellow circles) and B-type stars (blue diamonds). Isochrones at 1, 2, 3, and 5 Myr are overlaid in both cases, with 8 Myr also used for the MEDUSA region. The isochrones are based on rotating (ν_rot = 300   km   s^-1, dashed line) and non-rotating (ν_rot = 0   km   s^-1, solid line) evolutionary models of Brott et al. (2011) and Köhler et al. (in prep.). The ZAMS positions for stars with M_init = 20, 40, 60, 80, 100, 120, 150, 200, 300 and 400 M_⊙ are marked by black stars and joined with a solid line.