The Nome King was arguably brought to the screen in Return to Oz, but it was hardly an accurate portrayal of Baum's biggest arch-villain. Shown onscreen as a giant Claymation creation who gradually humanized into Nicol Williamson, this was not the evildoer readers knew and loved. Roquat of the Rocks was always more of a traditional dictator caricature, short in stature and temper but lofty in ambition. An underground fairy upset with the surface dwellers who dig for precious stones, he seeks revenge first against the nearby land of Ev, and then Oz. Fortunately for all, his easily accessible secret weakness is eggs.
With Oz being strictly nonviolent, Roquat is dealt with multiple times by being tricked into drinking from the Fountain of Oblivion, which wipes his memory clean, and first time around, causes him to rename himself Ruggedo. Nature versus nurture being what it is, however, along with the demand for popular villain reprisals, he always remembers his essential villainy eventually.
4. The Glass Cat
Yet more proof that Baum was probably a cat owner, this transparent feline has a tendency to yammer on and on about her pink brains and how you can see them work. Your own pet may not be able to articulate the thought quite as well, but you know s/he's thinking it.
This particular cat's inorganic nature comes in handy, though, when an enchanted island in The Magic of Oz causes all meat-creatures to grow roots and start shrinking into the ground. Unaffected, the conceited kitty is able to help save the day.
3. The Good Witch of the North
No character from the original Wonderful Wizard of Oz has been so shafted as this grand dame, named Locasta on the stage and Tattypoo by a shamelessly retconning sequel writer. Originally, she was the one who met Dorothy in Oz and set her on her quest.
Combining her with Glinda simplified things for the movies, but also made the plot an exercise in sheer sadism - knowing full well how Dorothy can get home, the movie's Glinda reveals nothing simply so Dorothy can learn a valuable lesson in self-worth at the possible expense of EVERYONE IN OZ, while the North Witch in the book simply doesn't have any awareness of the answer, nor have the power to do much of any effect.
2. The Woozy
No, the name does not imply a state of semi-consciousness - Baum specified that the double-o was to be pronounced as in "good," rather than "boozy." The creature by that name is a classic example of cartoonish bait-and-switch - before encountering him, characters are told that he's a dangerous, fearsome beast who can flash fire with his eyes and has a mighty roar. The roar turns out to be a squeak, and the creature a square thing whose body looks like it's made from boxes.
As for flashing fire, the Woozy only does that when it hears the phrase "Krizzle-kroo" enough times, because it gets mad that the words have no comprehensible meaning. Such a sensible monster it is.
Chopfyt is easily the most severely fucked-up character in the entire Oz canon. Seriously. But to tell his origin, we have to backtrack.
You know the Tin Woodman, but did you know he used to be a human named Nick Chopper? He fell for a girl named Nimmie Amee, but she was a servant for the Wicked Witch of the East, who had no desire to spare the help. So she enchanted Nick's blade, making it gradually cut of his limbs, each of which, cyborg-style, he replaced with tin appendages. Eventually he lost his heart, and with it his love; years later, Dorothy would find him and he'd regain it.
Meanwhile, a soldier named Captain Fyter fell for Nimmie, but the same thing happened: bad witch, bad spell, Fyter's sword slashes off all his limbs and they're replaced with tin. Nimiee is willing to marry him anyway, but he rusts in the rain and never makes it.
Years after that, the Tin Woodman goes searching for his lost love, encountering Fyter along the way, and both wish to see who the girl will truly want to be with.
Here's where it gets twisted.
They find her living with - and married to - Chopfyt, a Frankensteined creation made of the glued-together appendages of Nick Chopper and Captain Fyter. This is a prime example of how kids will just accept some really twisted shit, while grown-ups recall Lucky McKee's May. Nimiee is content to have the best parts of both suitors combined in one grotesque freak of nature, and both Tin Men realize they're better off not hanging with such a deranged bitch.