So, in Vegas this weekend, will I see Elvis? How many people dressed like Elvis will I see? What’s the plural of Elvis? A lot of people use “Elvii” but according to Bookdwarf and Straight Dope that would be assuming a spelling of Elvus. That’s the same as thinking the plural of penis is penii.
The -is ending is usually for third declension nouns, which are pluralized to -ites, so if we wanted to go the Latin route, really, we’d have Elvites. Of course, Elvis isn’t actually a Latin word, so the real plural is just Elvises, same as pelvises and penises.
The next question, then, is how many people are going to find this site looking for pornography and find ridiculous grammar instead? And is it going to be (shudder) Elvis porn? Possibly featuring the aliens who abducted him? I hope not.