The purpose of this analyses is to explain, in several different ways, the full name of the Mario brothers. I will also discuss why the title of the plumbers is in fact "The Mario Brothers".
First of all, let me explain something. I am a complete Luigi lover, so this report is tainted with Luigiest thinking. You have been warned. I will display several possible last names and first names for the Mario Brothers, and my arguments for or against them. My fellow Mariologests will have to decide for their own.
Now let's discuss are favorite plumbers' accepted names. Mario Mario and Luigi Mario. The first time I saw this theory I burst out laughing. I mean, give me a break. Mario Mario? Maybe it's the custom in Italy to name your children by their last names, but I seriously doubt it. If there are any Italians among you Mario fans, you're welcome to contact me and set me straight if I'm wrong. Maybe their parents were simply really, really desperate for a name for their children. Anyway, I soon discovered that this was the commonly accepted name for the Brothers, and I'm pretty sure that Miyamoto accepts it as well. Well, I don't know about you, but I think that if this is Mario's name, he must have been beat up at a lot at school. And if he was, than don't you think that Mario would be the "shy one" in the games, and Luigi would be the prominent hero in them? All that aside, this is definitely the simpleton's way of naming Mario. The only benefits it has is that it would explain why the brothers' title, "Mario Brothers" is named after the apparent name of only one of the plumbers, as opposed to "Mario and Luigi Brothers", as ridiculous as it sounds.
Another possibility is that their last name is "Mario" and Mario's first name is something else. Several possible Italian names are: "Enzo" "Folco" "Rolando" or "Vincenzo" (Note: These are all random names that have nothing to do with the games. I found them on Kabalarians.com. Now that is a cool site!) This is a doubtful theory, for a few reasons. One is that Baby Mario was named... well Mario. And obviously Baby Mario and Baby Luigi were given their last name when their Italian parents adopted them. I think that we can say that the name "Mario" is Mario's first name.
The third and most probable theory is that "Mario" and "Luigi" are their first names and they have a different last name. I have two possibilities for this name. Juliet and Kirsty Singleton’s wonderful fanfic, “Luigi’s Story”, suggested the first to me. The fic suggests that are heroes' names are Mario and Luigi Nintendo. This is a nice theory, since Mario is Nintendo's mascot. However, there is nothing in the games to prove it, so it is merely a possibility.
The second possible last name is one I myself thought of. It goes way back to Mario's debut, the simple but fun "Donkey Kong". The name "Mario" hadn't existed, and the tiny sprite that jumped over barrels and climbed ladders was named "Jumpman". Miyamoto could have been calling Mario by his last name. Therefore, the brothers' names would be Mario and Luigi Jumpman. I know, I know it's not Italian, but it's also a possibility...
The only problem with the last name theory is that it doesn't explain why they are called "The Mario Brothers". The simplest answer to this (In my strong Luigiest eyes) is that Mario is so egotistical and jealous of Luigi's superior wit, common sense and talent that he has pushed his milder brother aside and taken the name, the game and the fame for his own. Luigi obviously takes this in his stride, but will occasionally vent his frustration on Mario in a fistfight.
Thus concludes my analyses. If you have anything else to say on the topic, please e-mail me, or write your own report.