The real hero of "The Avengers" is not Iron Man, Thor or even Nick Fury. It's Joss Whedon.The film's director has managed to pull off the Herculean task of blending four huge Marvel Comics film franchises in such a way as to give each character time to shine, both individually and as a group. He even found time to toss in some of the trademark humor that made Whedon a king of the geeks with his "Buffy the Vampire Slayer" series.There's not a wasted frame. Whedon lays down just enough back story in case some newbie wanders into their first comic book movie. He quickly updates the lives of Iron Man, the boisterous billionaire played with egotistical fervor by Robert Downey Jr.; the All-American Captain America, brought to life with charm and humility by Chris Evans; the mighty (in so many ways) Thor, played by Chris Hemsworth; and the Hulk, played this go around by Mark Ruffalo.The team is brought together -- along with the spunky Black Widow (Scarlett Johansson) and determined Hawkeye (Jeremy Renner) -- by Nick Fury (Samuel L. Jackson). Thor's mischievous brother, Loki (Tom Hiddleston) has put together an alien army and wants to turn Earth into a slave world.This good vs. evil approach has been the standard blueprint for all of the characters in their own movies. The trick here is how Whedon cleverly cuts heroes from the herd -- Thor and Hulk, Captain America and Iron Man -- to bicker, battle and become allies. It shows that while the characters are flawed, they can put those problems aside when a larger threat looms.Whedon also maintains the best of what has made the Marvel comic book franchises so popular by exploiting the personal foibles that help make these characters so different from the swaggering heroes who had come before.It's the insecurities of Tony Stark that makes Iron Man both a leader and a rogue. It's Thor's quest to find his place between gods and men that make him relatable.This is particularly well played out with The Hulk. Past attempts to bring the big, green fighting machine to the big screen have ranged from Ang Lee's 2003 ludicrous directing efforts to Edward Norton's brooding version in the 2008 attempt. Whedon takes a smarter approach and allows The Hulk's human side, Bruce Banner (Ruffalo), to have a little bit of a sense of humor. He's a man conflicted, but he doesn't try to carry the angst of the entire world on his big green shoulders.As if that wasn't enough, Whedon also gives some peripheral character -- such as Agent Phil Coulson, played so well by Clark Gregg in small roles in several of the comic book films -- to have their moments. There is a particular sweet exchange between Coulson and Captain America about trading cards. It's in those moments that we're reminded of Marvel's original creed -- these people may have super powers but inside they have many of the weaknesses and strengths that come with being human.Whedon caps it off with a battle scene that's pure adrenalin rush. When it's all over, you may need a break, but don't go sprinting for the exits when the credits start. There's a good reason to hang around.Whedon might not wear a cape or a Spandex outfit, but his efforts to bring "The Avengers" to the big screen make him a champion. "The Avengers" is marvelous.