The thing about writing villains for children’s media is that much of the villainy is often implied. Villains make violent threats, but are rarely able to carry them out, for whatever reason. That way they can be seen as evil without actually doing much on stage. There are exceptions, of course; I mean, Harry Potter is a children’s series, and Voldemort is constantly killing people. In the Oz series, however, L. Frank Baum claimed he wanted to leave the heartaches and nightmares out. I’m not sure he always succeeded at that, as even in the first book he has the characters pitted against wild animals bent on their deaths. The heroes survive, but only by killing these animals. Later, however, Baum tended to go for less violent but still nasty actions from his villains, often involving magic. A good example of this is his recurring villain, the Nome King. I’ve seen it argued before that old Ruggedo isn’t really that bad, and he’s certainly not some creature of pure evil. Indeed, when he encounters the Phanfasms, said to be purely evil, he’s terrified of them. On the other hand, he’s tricky and not someone to be trusted. When he first shows up in Ozma of Oz, he comes across as good-natured and well-informed, but there’s an underhanded personality lurking below that.
He claims to have bought the royal family of Ev fair and square, and to have transformed them into ornaments so they wouldn’t have to be slaves. Never mind that he’s on rather shaky moral ground when it comes to buying and selling human beings. Just because King Evoldo of Ev was worse in some respects (he’s said to have beaten servants to death) doesn’t put Roquat in the right. He also claims he’ll let Ozma and her companions go free with the Evians if they succeed at a guessing game, only to threaten them with his army when Billina learns the secret. Still, it’s technically Ozma who’s the aggressor here, and while I can’t fault her for her humanitarianism, we can still see Roquat’s point of view. When we see him again in Emerald City, he’s completely full of rage, with none of the friendly front he had before.
He’s intent on conquering and laying waste to Oz, although there is one rather interesting passage where he claims he’ll turn Ozma and Dorothy into mantle ornaments instead of forcing them into slavery. Tik-Tok makes him a bit more sadistic, in that he employs a band of executioners who use implements of torture. They never get to do anything, and Ruggedo (this is after his name change) still seems to prefer transforming his victims rather than hurting them physically, but they’re still there. After his defeat in this story, he acts rather humble and is grateful to anyone who helps him, but we know it won’t last.
The Nome appears in several more books, but I don’t think it’s necessary to detail his actions in every one. Suffice it to say that he keeps on threatening, but the worst actions he actually commits tend to be transformations that are eventually broken. It is perhaps telling that there are several occasions when Baum presumably wanted to have the Nome King reform, only to bring him back as a villain, probably because he was more interesting that way. Later authors have also tried to reform the former Metal Monarch, perhaps seeing some good in him. If he had been a mass-murdering sort of villain, authors and readers might not have been so eager to occasionally highlight his good side. Then again, someone did recently write a book where Hitler goes to Oz.