How did Mario get his name? You may be familiar with the official story, that it was based on Nintendo of America landlord Mario Segale, but that may not be the whole story. It's just the easy version.
According to an impressive and exhaustive look at some of the more famous video game characters—and plenty of not so famous characters—that name may be based on the Japanese word "marui." Same for Luigi, or "ruiji." That's just the tip of the iceberg in Drew Mackie's list of video game character naming etymology, full of well researched trivia and theories about how Link, Zelda, Ken, Ryu and others came to be called by those names.
It's an incredibly long read, delving into franchises from Final Fantasy to Sonic the Hedgehog to Castlevania, one definitely worth reading.
My favorite theory is that of the Metroid species that appears in Kid Icarus, the Komayto. Fascinating!