One literary figure that would make an interesting and complex essay is Huckleberry Finn. Like Chris McCandless, he escaped the boundaries of conventional society and traveled (although not alone) to find his purpose and to find reason in a world that made little sense. Finn found himself at odds both with society -- which wanted him to conform to their standards -- and with non-society -- the drifters and scam artists who tried to exploit him. There is a quote from Twain in the text, and it is mentioned that Twain was one of Chris's favorite authors.
To compare and contrast with the existing parallels between Into the Wild's Chris and Grizzly Man's Timothy Treadwell, the focus of the essay should be on the desire to rid oneself of societal boundaries and become a self-reliant, free person, regardless of the social or personal costs. By moving from "the world" to "the wild," all three of these people found themselves connected to some higher purpose: for Chris, it was the peace of living freely; for Timothy, it was the protection of grizzly bears; for Finn, it was the protection and ultimately salvation of Jim the slave. All these things would have been impossible had they remained in their designated places; all three had first the drive to live unconventionally, and then the courage (or wilful ignorance) to jump into the deep end of nature with both feet.