Metallicity: What are the metallicity values of various galaxies? What are the various values of metallicity of various known galaxies, like Milky Way, Large Magellanic Cloud, Small Magellanic Cloud, Andromeda and so on?
metallicity is a complicated issue, and giving just one number (usually Z, but also 12+log(O/H), ...) is very rough. But, here are the standard values for the Magellanic clouds:

LMC: Z~1/2 

SMC: Z~1/5

with Z=1 being the solar value. Practically, the values will vary across any given galaxy (the Milky Way also has a metallicity gradient). 

Reference: 

Madden et al. 2014, PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 125:600–635, 2013 June
http://adsabs.harvard.edu/abs/2013PASP..125..600M

The article is also available on astroPH