There are good years, and then there are great years, and then there are the kinds of years that Joss Whedon had in 2012. In May, Lionsgate released Cabin In The Woods, the long-delayed, widely acclaimed po-mo horror flick, co-written and produced by the cult pop auteur. (Drew Goddard co-wrote and directed the film.) In July, Whedon attended Comic-Con and celebrated the tenth anniversary of his gone-too-soon TV series Firefly at one of the most emotional panels the annual fan-fest has ever seen. In September, Whedon went to the Toronto International Film Festival and premiered Much Ado About Nothing, a micro-budget, literally homemade adaptation of the Shakespeare comedy. ”That was an incredible experience,” recalls Nathan Fillion, who stars in the film (set for release next summer). “The man got three standing ovations before he got on stage. That’s just indicative of the kind of fandom that Joss creates. I have never seen anything like it.” In October, The CW aired – for the first time on television – Whedon’s 2008 Emmy-winning online opus Dr. Horrible’s Sing-Along Blog. Shortly before Halloween, the man who created Buffy The Vampire Slayer, Angel and Dollhouse took to the Web to say a few words about the defining issue of the 2012 presidential campaign – a zombie apocalypse – via a very funny, very personal, very partisan video viewed by over 7 million people.

Oh, and there was Marvel’s The Avengers. Whedon wrote and directed that, too. Grossed $1.5 billion worldwide. Maybe you saw it.

In an interview with EW for our Entertainers of the Year issue, now on sale, Whedon said a year of overwhelming success has left him feeling extremely grateful, a little tired, and more busy than ever: We met with him just days after he had submitted an outline for the 2015 sequel The Avengers, and as he was in the midst of preparing to shoot the pilot for what could be his next television series: S.H.I.E.L.D, a spy-fi drama tracking the ongoing adventures of the secret agents and superhero wranglers of Marvel’s movie world. If ABC he picks up the series, Whedon will remain involved as exec producer, and frequent collaborators Jed Whedon, Maurissa Tancharoen (Dollhouse, Dr. Horrible) and Jeffrey Bell (Angel) will serve as lead showrunners.

Yet Whedon says that his emotional reaction to his most Marvel-ous year also included “a little bit of anger.” He elaborates: “I’ve had a wonderful career, and I’m grateful for it. But like every writer in Hollywood, there have been many times where I’ve said, ‘I swear to God, if you just me do this the way I’m thinking of doing it, it’ll work out!’ and I’ve been thwarted.” The success of The Avengers, then, felt like validation, but also exposed his need for validation… as well as a deep, dark want to avenge old grievances with black magic necromancy. “Once you get to this place, where people will listen to you, give you the benefit of the doubt, and will get out of your way, all of the stuff you’ve learned to live with and tamped down, you don’t need to live with it anymore” – and here, he goes spooky voice to evoke an image of summoning ancient demons – “and so the basement door opens … and you go down into there … and read from the diary that raises the dead.” He laughs. “It’s a weird little counter-intuitive thing.”

In retrospect, Whedon sees his anger — about life in general, not just old Hollywood slights — reflected in The Avengers, and specifically in one of the film’s best-realized characters: The Hulk, played by Mark Ruffalo. “What was most astonishing to me about making that movie was how personal it was,” he says. “I literally had the I’m-always-angry revelation during production. I had this certain amount of back-burner simmer of rage that I was completely aware of, but apparently I wrote it for Bruce Banner, going (to myself): ‘I think this is what a guy like this might go through!’ Interesting! What guy, Joss? ‘I don’t know! Some guy. I can’t think of anyone in particular, or why this is coming to me…’ Really, Joss? Really?”

To be clear: Whedon thinks going totally Loki is a thing to be avoided. “For the most part, I’m psyched. But you have to be careful that self-righteous umbrage doesn’t determine how you act around people, or how you behave artistically,” he says. “You don’t want to be the guy who’s like: ‘OF COURSE I’M RIGHT! I’VE ALWAYS BEEN RIGHT ALL ALONG!” And then suddenly, you’re making your worst stuff, because you’ve lost that checks-and-balances thing you need to manage yourself.”

We’ll have more of our interview with Joss Whedon in the coming week. For Nathan Fillion’s tribute to Joss, check out our Entertainers of the Year issue, starring Argo triple-threat Ben Affleck, on newsstands now.