Joss Whedon: The Complete Companion: The TV Series, the Movies, the Comic Books and More: The Essential Guide to the Whedonverse - PopMatters

I adore Joss Whedon and already own a few books about his series. This one was written just before Cabin in the Woods and Avengers came out so I wish there was more on those. I do recommend the book however if you haven't read/watched everything by Joss Whedon I would be wary since there are spoilers galore, even in other sections.