Graphic novels are a little different than the popular genre, Manga. Graphic novels are stories told in pictures. It's a bit like the story board for an animated movie. They read from left to right just like a traditional book. Some maintain the original text while others paraphrase the text to make it easier to read.
To get started, you may try some Shakespeare. Romeo and Juliet is always popular. I know of a student that once wrote a paper on Romeo and Juliet. They read the graphic novel, the play, and watched more than one version of the movie. They finished by comparing the story to the musical West Side Story.
Other Shakespeare graphic novels include: Twelfth Night, Much Ado About Nothing, Macbeth, and Midsummer Night's Dream.
Another classic author that is represented on our shelves in graphic form is Henry David Thoreau. His work Walden inspired the graphic novel, Thoreau at Walden by John Porcellino.
Finally, for those who love mythology, we have several graphic novels that feature the gods. Two examples include: Beowulf and The Odyssey. Both are adapted and illustrated by Gareth Hinds.