I'm going to keep the graphic novel category going and pick Art Spiegelman's landmark pulitzer-prize-winning series, Maus.
It tells the story of Art Spiegelman's father, a Aushwitz survivor, as well as the difficult relationship between father and son. Spiegelman explores clever use of anthropomorphism throughout the story, and simple, elemental drawings. The narrative flips through time from the concentration camp to through to the modern day, and stops in between. Far from sentimentalizing his father, Spiegelman portrays him as difficult, beligerent, and occasionally racist. It's a very personal and moving work in both story arcs that it deals with.
This isn't the first graphic novel of its style, but it definitely took the adult non-fiction graphic novel mainstream, and in my mind it's deserving of all the accolades that it received.