  We used a combination of optical and near-UV Hubble Space Telescope
photometry and FLAMES/ESO-VLT high-resolution spectroscopy to characterize the
stellar content of the old and massive globular cluster (GC) NGC121 in the
Small Magellanic Cloud (SMC). We report on the detection of multiple stellar
populations, the first case in the SMC stellar cluster system. This result
enforces the emerging scenario in which the presence of multiple stellar
populations is a distinctive-feature of old and massive GCs regardless of the
environment, as far as the light element distribution is concerned. We find
that second population (SG) stars are more centrally concentrated than first
(FG) ones. More interestingly, at odds with what typically observed in Galactic
GCs, we find that NGC121 is the only cluster so far to be dominated by FG stars
that account for more than 65% of the total cluster mass. In the framework
where GCs were born with a 90-95% of FG stars, this observational finding would
suggest that either NGC121 experienced a milder stellar mass-loss with respect
to Galactic GCs or it formed a smaller fraction of SG stars.
