Spot-on! Mavros is the anglo-phonetic version of "Mauro" which is means Black in Greek. Mauritania, Maurice, etc, are indeed derived from "mauros". Mauros itself derived from the even more Ancient Greek "amauros" meaning "dim, faint, ambiguous (metaphorically)".
Kara- , which appears as a prefix in some comtemporary Greek surnames, means "black" in Turkish.
While on the subject, its worth noting that Ethiopian "Aithiops" literally means "sun-burnt face" from "aithein" (to burn) and "ops" (face).