Maus

Maus is one of the most well-known graphic novels in the history of comics, and it has that distinction for a very good reason. It is a sometimes light-hearted, sometimes starkly serious examination of the Holocaust as experienced by the father of the author, Art Spiegelman. It employs an extended series of clever visual metaphor, in which different racial and national stereotypes are represented with animal heads, most notably mice for Jews and cats for Nazis. This metaphor is played and even mocked in several places, including a humorous conversation between Art and his wife (a Jew through conversion) on whether she should be represented for her Jewish status or her French heritage.
It's notable that this is just as much Art's story as it is his fathers, with the screentime split between the past events in Auschwitz, and the present of Art's emotional conflicts dealing with his father both during his final years and after his death. The fourth wall is frequently ignored and even taunted, with characters admitting that some things are altered for clarity ("You never would have let me talk for this long in real life") and Art's frequent struggles on the difficulty of presenting the Holocaust in an accurate and respectful manner. There is an especially powerful moment at the very end where we are suddenly given a real photo of Vladek Spiegelman, as if reaffirming the reality of the story we've just been told. Art's portrayal of his father is especially notable, as he simultaneously shows respect and resentment toward him, and does little to censor his less admirable features, such as pettiness, racism, and a long history of guilt-tripping.
Through the presentation of his father, we are also granted insight into Art's nature, as he lies in the very first chapter, promising not to publish the story he had just finished relaying to us. Snippets of things such as an early, emotionally charged comic of his, regarding his relationship with his mother, and Art reflecting on the portrait of his dead older brother, reveal a lifetime of self-loathing and resentment. This is brought to an extremely fourth-wall shattering moment when Art addresses the reader on the aftermath of the first volume's publication, visually shifting back and forth from a child to adult as his sense of self-worth weakens amongst the growing media documentation surrounding his story.