There are several other famous conquistadors other than the ones you named. De Soto, Vasco de Gama, Balboa, Coronado, etc. You could even count Columbus.
Could you accept more spellings for Ericson? I tried Erikson, Eriksson, and Ericsson before finally getting the one you wanted. Wikipedia uses Erikson.
I agree. His name in the *original* norse was spelled Leiv Eiriksson i believe, so accepting more spellings would be helpful. And same with Erik the red