The main character Gwynplaine in Hugo's The Man Who Laughs, whose face was disfigured into a laughing mask as a child, falls in love with a blind girl named Dea.
The 1928 film (including the anachronistic Ferris wheel) The Man Who Laughs serves as important link to the modern representations, a direct precursor of the Joker.
In the 1970s, Bob Kane acknowledged the inspiration for the Joker, and it was later explicitly referenced in the graphic novel, Batman: The Man Who Laughs. Comic book artist Brian Bolland said that watching The Man Who Laughs was one of his inspirations for drawing the graphic novel Batman: The Killing Joke (1988). In the 2003 "Wild Cards" episode of the Justice League animated series, The Joker infiltrated a TV station by using the alias "Gwynplaine Entertainment". (Other copycats, see here.)
Also, according to a French blog, a David Fincher movie has a shared fate of his Se7en character played by actress Gwyneth Paltrow (whose first name resembles Hugo’s Gwynplaine, and was often slated as a Catwoman candidate), eerily echoes the not-so-happy ending of Blanche, the secret daughter of Verdi's Rigoletto (also inspired by Hugo). Source.
Meanwhile, over in the Netherlands, there is news of the trial of a Joker copycat killer.
An artist's impression of Kim De Gelder on the first day of his trial at Gent's courthouse on February 22, 2013. A nursery killer disguised as Batman villain The Joker told a court he was left "no choice" but to stab to death two toddlers and their caregiver at a Belgian creche -- despite saying he knew murder was wrong. Source.
De Gelder is charged with killing the two infants and their 54-year-old carer in an attack on the Fable Land nursery in the town of Dendermonde in January 2009, as well as the attempted murder of 22 others at the creche -- including 16 babies and toddlers. De Gelder is further charged with murdering an elderly woman in a separate attack a week earlier.
Just after the release of cult 2008 Batman movie The Dark Knight, De Gelder entered the nursery with his hair dyed red and his face painted white with black around his eyes -- like the film's villain The Joker, as played by the late Australian actor Heath Ledger.
Please also see Joker Copycats, 2008-2012, and the immediate Aurora Copycats, which included some Joker Copycats.