Is it ok to reg Greek or Roman God, King or scholar names?

Is it ok to reg some ancient names of Greek or Roman God, King, ruler, Scholars, soldier. I think many companies uses these ancient names, so I wonder is it legal to hand reg if some names are still available. for example NIKE, EROS, IRIS these are the name of Greek Gods and Goddess.

Is it ok to reg Greek or Roman God, King or scholar names?