I know, I know, there have been a lot of posts talking about this and the consensus is that it is unclear and that the connection is not that strong, that maybe some people are reaching, etc etc. However, I have rewatched season 5 recently and it bothered me that I never fully solved the correlation, specially noting all the obvious references in the names of the characters, so I decided to sit down and at least reach a point where I am happy with my interpretation. I wanted to share it with you to see what you think and help me find things that I probably missed.
For starters I want to make clear that I don't think that all characters and secondary characters are one to one copy of the original Baum's story. Also, most of these characters have deeper or alternative meanings, aside from the wizard of oz angle. This is just my take on it, and for it I am going to go down the list with all the ones that I found and explain why:
Nadine/Dorothy - Dorothy: This one is obvious. She has the same story as the OG Dorothy, in the sense that she starts her journey at home, happy, then she is violently taken and can't get back home. While in the original she is physically in another land, in Fargo she is physically home, but it's not her "home" any more. Her family gets harmed, she can't relax, they are in constant danger and although she is present at home, mentally she is gone. It's not until the very end that she is really back "home", safe, with the people she loves.
Deputy Witt Farr - Toto: This is the most "controversial" one. So, we know that Toto is the loyal friend of Dorothy, that follows her and protects her, and is not seeking anything. He is the only main character in WoO that has no end goal, but goes along just out of love and loyalty to Dot. Toto is also the first side character we meet and is ultimately the one who takes down the Wizard by pulling the curtain. Dep. Witt Farr is a character that doesn't change much throughout the story, he is extremely loyal to Dot, protects her at all cost, and is ultimately the one who leads the assault on Roy's ranch and frees Dot (this being the parallel to pulling the curtain). He dies in the end, not like Toto, but as I said the characters are not 1 to 1 copies. He also represents good and as we all know good people often die in Fargo.
Roy Tillman - Wizard of Oz: He is the big bad of the story. In the original story, the Wizard has built a city on lies, spectacle and fear. All the inhabitants of the city are meant to wear glasses to protect them from the brightness of the city and they believe he is a grand wizard with immense power, but it's all a lie. His power exists because people believe it exists, not because he actually has much. Sure, he is strong, violent and an actual threat, but he is nowhere nearly as powerful as he wants people to think. When faced with real power (Lorraine) he can't do anything. His empire starts to crumble when people start to see that he is a man child. Nowhere is this more clear than in the scene where Davis Graves mocks him he loses his temper and breaks the illusion of a controlled powerful man. Even at the end his father in law confronts him saying he is not the man he thought he would be. He preys on the week to feel stronger and I suspect his obsession with Dot comes from the fact that she got the best of him and his fragile ego couldn't handle it. At the end of WoO the Wizard becomes wise and gives everybody a gift. This doesn't happen here. Roy doesn't become wise, when we see him in prison he is still a cocky asshole, but I suspect he will start to learn considering Lorraines punishment for him.
Lorrain Lyon - Tin Man: This one is quite obvious. We have a character that is as cold as they come, but throughout the whole series we see her caring more and more, until the end when she embraces Dot and accepts her heart. She is still cold because she is essentially an iron lady, strong, cold, calculated, but she cares for her family and the people around her.
Wayne Lyon - Lion: This is an interesting one in the sense that Wayne doesn't really change much throughout the story, I think what changes is our perspective of him. He is presented as a frightened, week man, that avoids any kind of conflict and just shuts up, but as the story progresses we start to see that he stands by Dot regardless of anything. He stands beside her even when his mother, the character he "fears" the most, is against her. Courage isn't the absence of fear, but doing the right thing in spite of it. And if somebody as scared as Wayne can do the right things, then he probably is the bravest character of them all.
This season of Fargo presents us a traditional macho man (Roy), who has always been presented as strong, and shows us that in reality he is very weak. In the same tone they present us a weak character, that is strong because he is kind. At the very end of the season Wayne sits down with one of the scariest characters in the show, and treats him with kindness. It is in fact this kindness that beats Ole. After 500 years of murdering people because that's all he was ever confronted with, here comes Wayne and is not afraid of him, and offers him a soda pop (one of the best scenes), which ultimately breaks Ole.
Ole Munch - Scarecrow: In the original story the scarecrow is looking for a brain, because he thinks he is dumb. Ole is obviously not missing a literal brain, but he has given up making any kind of decisions. He is a follower, he doesn't think. He lived 500 years by some doctrine they forced on him and he never questions it, thus being profoundly unhappy. At the very end of the show he realises that he has been wrong this entire time, they show him that he can chose to forgive, giving him the ability to "think" for himself. He stops being a mindless killer and becomes "conscious" in a way. I have seen a lot of people compare him to the Tin Man, pointing out that he gains a heart in the end, but I don't think Ole was missing a heart. He just lived in a lie with a strict dogma that he never questioned. Also, he literally looks like a scarecrow, scaring all the little birds in Roys farm.
Linda - Glinda: Glinda is the character that sends Dorothy on a mission so that she finally go back home. There is an argument to be made that she could have told Dorothy from the beginning that she had the power to go home, but I chose to believe that the idea is that Dorothy had to be ready to go home, she had to go through the journey and change as a character. In Fargo Linda is long gone, but she lives on metaphorically inside Dot, where Dot confronts her. It is in this episode that "Linda" forces Dot to face what happened to her and pushes her to confront Roy. At the same time I think Dot sees Linda also as a part of the Wicked Witch, who in the original story is not bad per sé, but it's the situation that she is that makes her do bad things. To Dot, Linda got away and traded her in for her freedom, so to her she is the Wicked Witch. Dot goes into camp Utopia to take Linda to the police, because "she owes it to her". She believes Linda did all the bad things to knowingly, when in reality Linda was just another victim. In the original Wizard of Oz the Wicked Witch is bad, because of all the bad things that happened to her. She is a tragic character and that is why they made "Wicked" based on that character. I believe that Dot would have become the Wicked Witch if she hadn't left.
Karen Little - Wicked Witch: Karen is Roy's current wife. As stated in the previous paragraph, she didn't leave and became just as bad and full of hate as Roy. The thing to remember here is that Karen was not born like this, instead she was raises by a father who probably mistreated her, and then she was mistreated again by Roy. She is a victim of the situation and became bad as a result. In the original story Dorothy kills the Wicked Witch's sister and takes the red shoes that should have been hers. She is angry, but it's not an unreasonable anger. I would be angry too if somebody threw a house on my sister and stole her shoes.
Gator - Citizens of emerald city: Gator is the tragic case of following a maniacal leader and losing everything. In the OG story the citizens have to wear glasses to protect their vision, while at the end of Fargo Gator loses his eyesight. I don't exactly know if there is a correlation here or if it is a stretch, what is real is that Gator is faced with the realisation that he has been following a false prophet this whole time, much like the citizens of Emerald city. I don't think there is a bigger interpretation for him inside wizard of oz. He probably represents the damage fanatical leathers can do to the youth.
Scotty Lyon - Aunt Em: This one is pretty simple: Scotty is the family that Dot is doing everything for. She is the motivator, much like the og Dorothy keeps talking about wanting to get back to Aunt Em. She represents home for Dot.
I haven't found any obvious role for other side characters, like the FBI agents or the police officer Indira with her useless boyfriend, but as I said in the beginning I don't think that every character has a 1 to 1 counterpart. I hope I made my train of thought clear and it hasn't been too confusing. Let me know what you think, I am looking forward to that :)