The Most Massive Stars in the Local Universe

The lower limit to the mass of stars is well defined, while the upper
limit remains controversial. I shall summarise evidence in support of
the currently accepted limit, and present recent VLT-based studies of
the brightest members of young, nearby star clusters which argue for a
higher limit.  Consideration is given to questions of binarity using a
variety of methods, while we present simulations of star clusters
which argue for an upper mass limit close to 300 solar masses.  The
wider significance of this limit is discussed both for the integrated
properties of unresolved star clusters and the possibility that
pair-instability supernovae exist in the local universe, as proposed
for SN 2007bi.