Whedon, a favorite among fanboys, most recently penned the script for “Cabin in the Woods,” a horror pic that he is also producing for MGM. Pic co-stars Chris Hemsworth, who plays the hammer-wielding Thor.

The creator of series like “Buffy the Vampire Slayer,” “Angel,” “Firefly” and more recently “Dollhouse,” all for Fox, has been close to helming a superhero pic before, namely “Wonder Woman” for Joel Silver at Warner Bros., but Whedon wound up ankling the project due to creative issues.

He directed episodes of those series, and recently helmed an episode of Fox’s “Glee.” “Serenity” is his sole film directing credit. The sci-fi western, distribbed by Universal in 2005, was based on the short-lived “Firefly.”

“The Avengers” extends Whedon’s long relationship with Marvel. He wrote for the comicbook company’s “Astonishing X-Men” series.

“The Avengers” would star Robert Downey Jr. (as Iron Man), Chris Evans (Captain America), Hemsworth (Thor) and Samuel L. Jackson (Nick Fury). Edward Norton may also return as the Hulk.

“Iron Man 2” bows May 7, followed by “Thor” on May 6, 2011, and “The First Avenger: Captain America” on July 22, 2011. Paramount will distrib.