Played by Al Pacino, Michael Corleone is the biggest kahuna in this movie. Yeah, Vito Corleone is a pretty big kahuna as well—but Michael ends up taking the cake. He's the one who leads the Corleone family to its final (and really, really violent) victory.
Al Pacino was irritated that Brando received a Best Actor nomination while he only received a Best Supporting Actor nomination—even though Michael is actually on screen more frequently than Vito. In our "Hero's Journey" section, we follow Michael's trajectory, since he proceeds through more of the classic stages of the quest, with Vito functioning as his wise mentor.
Initially, Michael is a golden boy. He's a war hero from WWII, he has a girlfriend (Kay) who seems on track to become his wife, and he has a legitimate, non-criminal career in his future. "That's my family, not me," he tells Kay, referencing his family's murderous business. But circumstances intervene.
After the Tattaglia family tries to kill his father, Michael needs to steer off his law-abiding career path. In the process, he discovers he can be pretty cool under pressure, like when he protects his dad from another would-be assassination attempt at the hospital. Finally, he crosses over to the criminal side by murdering Sollozzo and Captain McCluskey, who both conspired in arranging the Don's failed assassination. He's committed to the Mafia Boss trajectory—even though he has to escape to Sicily.
In Sicily, he leads a pleasant and idyllic existence, marrying a Sicilian girl. But a car bomb kills her, puncturing his bucolic dreams. After his brother Sonny is assassinated, Michael returns to New York—all set to succeed his father as Don. He gradually sets about doing this, getting his chips into place and finally bringing down the wrath of God (or the Devil) on his enemies.
He orders a massacre that wipes out their leading rivals and the traitors within their midst, setting the Corleones up for supremacy among New York's five Mafia families.
Whereas the Don's other son, Sonny, is kind of an unprincipled jerk—full of intense animal energy—Michael is a much more calculating and savvy figure. Originally, his father wanted him to go legit, to live the American Dream in an authentic and non-criminal way and become a senator or a governor. But that's not what happens: Sonny ends up being a fairly lousy Don and gets murdered in the process.
A Philosophical Gangster
Michael becomes a very good Don indeed. The key to his success seems to be that, whereas Sonny takes things personally, Michael is able to keep his cool. As he says to his brother at one point, "It's not personal, Sonny. It's strictly business."
That's what should be engraved on Michael's tombstone, if they ever bring him down. He's a consummate Chess Master—he gets that revenge is a dish best served cold, and is able to bide his time before eliminating Carlo, thus avenging Sonny and Connie in one fell swoop. He's clever in a way that Sonny never could be.
But, hey, Michael's also a pretty bad guy by the time the movie ends. He's gained power, but lost his soul—arranging a massacre that wipes out all of his enemies, as he hypocritically makes pious affirmations at his sister's child's christening. He lies to his wife about his murderousness and seems set to lead a double life, trying to be a committed family man while simultaneously acting as a ruthless Mafia boss.
But can he sustain this contradiction? Tune into The Godfather Part II to find out. And if you're still not satisfied, you can tune into The Godfather Part III (we guess—it's nowhere near as awesome as the first two).