Using a combination of instruments on ESO's Very Large Telescope, astronomers have discovered the most massive stars to date, some weighing at birth more than 300 times the mass of the Sun, or twice as much as the currently accepted limit of 150 solar masses. The most extreme of these stars was found in the cluster R136 in the Tarantula Nebula. Named R136a1, it is found to have a current mass of 265 times that of the Sun. The origin of such monster stars is a challenge for the current understanding of star formation mechanisms.