Massive stars are fundamental and active drivers of the Universe because of their injection of energy, momentum, and nuclear-processed material in every single stage of their life and death. Prior to characterizing their feedback, however, we first need to answer urging questions regarding their formation, winds and evolution, all of which depend on chemical composition.
The GTC-OSIRIS combination is an excellent machine for quantitative studies of blue massive stars in Local Group galaxies, where different metallicity environments can be probed. We present our recent analyses of OSIRIS spectra of blue massive stars in IC1613 and M33, where metallicity ranges from $\sim$0.05 to 1.5 Z$_{\odot}$~ according to nearby HII regions. The results provide new insight for our models
of massive star winds and evolution in an unprecedentedly wide metallicity interval.