What are some famous monomaniacs that are fiction?

Captain Ahab from "Moby-Dick" by Herman Melville is a famous fictional monomaniac obsessed with hunting the white whale. Victor Frankenstein from Mary Shelley's "Frankenstein" is another example, driven by his obsession with creating life. Jay Gatsby from F. Scott Fitzgerald's "The Great Gatsby" is also a well-known monomaniac fixated on winning back his lost love, Daisy.