According to Kelly: "It's a story about a girl who's a bit of an outsider – she's funny, but totally in our geekland: she's obsessed with Dungeons & Dragons, she doesn't have a lot of friends, she's a bit of a social misfit. She's taken her fantasy life a little far, and really only talks about giants to people. She's convinced that giants are real and giants are coming, and it's her responsibility to stop them when they show up. This weird little fantasy life that she's going has started seeping into her real life, and as we see things from her point of view, we see that she sees pixies and she sees signs in the clouds and other things that might be telling her that bad things might be coming".[2]
I Kill Giants won the "Best Indie Book of 2008" by IGN,[3] as well as making it onto the list of the ten best comics of 2009 compiled by New York magazine's Dan Kois.[4][5] It was also a 2010 top ten great graphic novels for teens by the Young Adult Library Services Association.[6] It won the Gold Award at the 5th International Manga Award in 2012.[7] It was voted the second best foreign comic book published in Japan in the Gaiman Award.[8]