Setting: Not certain; generally, post-U.S. Civil War
Searched: "villains 19th century" "nineteenth century literature villains", "dime novel villains"
This is one of those early-story-gestation questions, so apologies for being vague and not searching extremely well beforehand.
I've recently finished a serious novel and now am in the mood to write something crazy fun for the Internet (not for profit), and I've decided to pursue the old "Tom Sawyer & Huck Finn grown up as steampunk detectives" idea that many people I'm sure have had. Going off on Alan Moore and LoEG, I have them interacting with several characters from literature, including a starring role for Jo March. But I'm in need of villains. I'm hesitating whether or not to use Fu Manchu as my main villain, since Moore did that in the original LoEG graphic novel, but I still would like more suggestions. I'm sure I want a sort of femme fatale, in the style of Irene Adler perhaps (but in this universe, like LoEG, all literary characters are real, so Holmes and Adler actually do exist in this continuity); some second- and third-level baddies; and henchmen, preferably the kind I can turn into zombie ninja robots or the like for big cartoon battles with no qualms.
This continuity takes into account "Tom Sawyer Abroad" and "Tom Sawyer, Detective", so the ages and timeframes of the characters, and thus their contemporaries in the world of literature, are kind of fluid.
All suggestions of characters welcome.
Edit: I've settled on 1869 (fudging Tom & Huck's birthdates a bit so that they're not almost forty) and starting off with Jo marching (pun) into their office to hire them to help find Amy & Laurie who apparently have been kidnapped by pirates in the Mid-Atlantic. "Apparently" is me allowing anything to happen. I've been convinced Nemo and the Nautilus will be involved, though friend or foe I'm not sure, and the adventure will go from the sea back into the States and all the way into some Western climax. Thanks for the suggestions so far, there's quite a few I can use, and keep them all coming--I'm probably not the only one who'd love to find characters like these from the time period! (Though one poster was right, I should be stricter in restricting it to 19th century lit, Gone With The Wind notwithstanding.)
Edit2: I've removed the "English language" restriction since I realized Jules Verne wrote in French. :)
Edit3: I am wholly embracing French-originated characters now I just discovered the works of Paul Feval. At this point, I am trying to pin down an archvillain.
YA Edit: A poster recommended Jess Nevins' Fantastic Victoriana, which I only knew as a book, not as a website that predated it, and which is like everything I need and more. What a resource!</b>