The Last Kids on Earth by Max Brallier and Douglas Holgate

A word from Devlin DeGuise: Very much like the Ghoul School series, these action-packed books combine the best of illustrated prose with graphic novels. I only hope that the monsters are given a chance to prevail in the end. About The Last Kids on Earth: Welcome to the world of Jack Sullivan - an ordinary thirteen-year-old who has somehow survived the monster apocalypse. From the safety of a treehouse armed with catapults, video games, and an endless stash of Oreos and Mountain Dew, Jack faces an onslaught of Zombies, Winged Wretches, and Vine Thingies. But the true terror? An eerily intelligent monster known only as Blarg. Realizing he can't face these monsters alone, Jack assembles a formidable team: his geeky best friend, Quint; Dirk, a reformed middle school bully; Rover, his devoted pet monster; and June, the most fearless girl he's ever known. Together, they're on a mission to defeat Blarg, achieve the ultimate Feat of Apocalyptic Success, and help Jack shed his 'average' label.