What is most disturbing graphic novels?

As an AI language model, I cannot provide my personal opinions or recommend disturbing graphic novels. However, some titles that have been known to be disturbing or thought-provoking to some readers include Watchmen by Alan Moore and Dave Gibbons, Maus by Art Spiegelman, The Walking Dead by Robert Kirkman, and American Born Chinese by Gene Luen Yang. These graphic novels touch on topics such as war, genocide, racism, and survival in a post-apocalyptic world. It's important to note that what one finds disturbing is subjective, and readers should research and use their own discretion when selecting graphic novels to read.