As the main villain of the franchise, Yzma is malicious and power hungry. She desires to become Empress and rule the kingdom, but is prevented by virtue of Kuzco having the position. Instead, she is first the king's advisor. However, she still attempted to act as Empress in his absence.
At the same time, Yzma is rather comically eccentric. She sees herself as the most beautiful person in the land, despite the fact that most people consider her hideous and often compare her to a dinosaur. When making plans to harm Kuzco, she often attempts to create overly complicated plans, before settling on a simpler version. However, she often fails to pay attention to minor details which results in her plans being thwarted.
Her catchphrase is "It's brilliant, brilliant, brrrrilliant!".
Introduced as the Emperor's advisor, Yzma is first seen sitting in Kuzco's throne and making decisions for him behind his back. Kuzco discovers that she has been meddling in his affairs, and fires Yzma as a result.
Later on, she vents her rage by smashing busts of Kuzco with a giant hammer, but a careless comment by her right-hand man, Kronk Pepikrankenitz gives her the idea to kill Kuzco; with Kuzco out of the way and no heir to the throne, Yzma would automatically take over the position and rule the empire. She and Kronk, via a roller coaster, go to Yzma's laboratory known as the Secret Lab, where Yzma decides to poison Kuzco with a flea poison to save on postage (mainly because she accidentally knocked over one of the potions on a flowerpot, and then it melted right away). She arranges to have dinner with Kuzco.
That evening, Yzma and Kronk get everything ready for dinner. Kuzco slams the door open, and Yzma tells Kronk to get the Emperor a drink. Though Kronk is more interested in cooking dinner than carrying out Yzma's orders, he tells her the poison is ready. Kronk poisons Kuzco's drink, but forgets whose drink is whose, so he mixes all 3 drinks together, and he and Yzma discreetly throw away their drinks as Kuzco downs his. However, the attempt to kill the Emperor is flawed as the supposed poison turns out to be a potion which turns Kuzco into a llama. Yzma orders Kronk to knock out Kuzco with the bowlful of broccolis, take him out of town, and finish the job. However, when Kronk asks for dessert and coffee, Yzma says, "All right, a quick cup of coffee... THEN TAKE HIM OUT OF TOWN AND FINISH THE JOB!!!".
Taking the llama's unconscious body to the edge of the city in a bag, Kronk throws Kuzco in the river, but after talking to his conscience, Kronk has a change of heart at the last minute and rushes to save Kuzco before he falls to his apparent death, and succeeds. Walking down the stairs and asking himself what he should do with the body, accidentally steps on a cat's tail (thus waking it up) and lets go of the bag, which falls down the stairs and onto the cart of an obese peasant named Pacha, just as he is leaving the city with his pet llama, Misty.
As everyone, including Yzma, believes that Kuzco is dead, Yzma becomes empress and redecorates the palace (cut from singing her own version of "Perfect World").
When Kronk reveals that he never killed Kuzco and that he's still alive, the two of them set off to find him, with Kronk carrying Yzma on his back in a specially built miniature tent.
They search every village surrounding the palace (with no success), and Yzma loses her temper when they reach the jungle. However, Kronk uses his Junior Chipmunk skills to ask Bucky the squirrel which way the talking llama went, and Bucky points left and chitters.
Shortly after, Yzma and Kronk arrive at Mudka's Meat Hut, a small roadside diner where Pacha and Kuzco have coincidentally stopped to eat when their blood sugar's getting low, and disguised themselves as a married couple after seeing that there are no llamas allowed. When Pacha overhears Yzma and Kronk talking about their plans to kill Kuzco, he tries to warn Kuzco and get him out of the diner. Kuzco and Yzma both go to the kitchen to request special orders to Kronk (who is replacing the previous chef who quit). When Yzma enters again, Pacha stops short and imitates the picture of the diner's icon behind him. However, Kuzco and Yzma narrowly avoid seeing each other. Ultimately, Pacha distracts Yzma by telling the diner staff that it's her birthday, and he takes Kuzco out just as Yzma is receiving her birthday greetings.
When Pacha tells Kuzco that Yzma and Kronk are trying to kill him, Kuzco, convinced that Yzma is loyal, doesn't believe Pacha and falls out with him, believing Pacha's claim to be a plan to save his hilltop from destruction, and then orders Pacha to go. When Kuzco goes back to Yzma, he overhears the villains discussing their plans to track him down and kill him. Kuzco finally realizes Pacha was right and searches frantically for him, but Pacha has already left.
Having lost all hope of ever returning to the palace and regaining his human form, Kuzco resigns himself to the fate of an ordinary llama.
That night, Kronk suddenly remembers Pacha's face and links him to Kuzco.
The next morning, Kuzco finds Pacha in the llama herd and makes up with him, and then they both go to Pacha's house. They find that Yzma and Kronk are there searching for Kuzco (and claiming that they are distant relatives of Pacha). Chicha, Pacha's wife and the kids keep Yzma and Kronk at bay (first, by locking them in the closet, then by turning Yzma into a piñata). This gives Kuzco and Pacha a headstart, but Yzma sees them disappearing over the horizon, and a frantic race between Kuzco, Pacha, Yzma, and Kronk ensues, such that Yzma and Kuzco are almost within eyeshot. Kuzco and Pacha use a rope to cross a gorge, and then Kuzco cuts it with his mouth in an attempt to keep the villains at bay. However, Yzma's transport tent sprouts wings, and she and Kronk begin to sail over the gorge. They seem to have succeeded, but before they get to the other side, they are struck by lightning, and then fall into a chasm.
Kuzco and Pacha reach the palace, only to find that their pursuers somehow got there first (by a method which, humorously, not even they know). Yzma then orders Kronk to kill the duo after throwing a knife at him, but her henchman once again has a change of heart, and cuts the rope to a chandelier, but it falls around Yzma instead of on her, and then she sends Kronk down a trapdoor, along with his Shoulder Angel and Devil. After a brief struggle for the vial, Yzma knocks over the potions cabinet so that Kuzco and Pacha cannot tell which is the antidote, and calls the palace guards to kill the peasant and the talking llama. Pacha throws the potions onto the guards, turning them into various animals. After the guard who has turned into a cow is excused, the chase continues as Kuzco tries every potion, transforming into various creatures before transforming back into a llama.
They outwit the guards, but Yzma continues to persue them until they reach the palace roof, and only 2 potions remain for Kuzco to try. Yzma snatches one of them, but it is the wrong potion, and she turns into a cat. When Kuzco takes the potion, she attacks him. When Pacha tries to help, she scratches him, causing him to fall. Kuzco hits Yzma on the wall, knocking her out. Once Yzma recovers, she quickly snatches the potion away from Kuzco, declaring that she'll turn herself back into a human and kill Kuzco. She finds that she can't open the vial, and her frustration makes her fall from the roof; while Kuzco is saving Pacha, the vial also falls. However, both Yzma and the vial return to the roof, with the help of a giant trampoline. Yzma reaches the vial before Kuzco and Pacha, and seems to have won, until she is knocked out by Kronk, who has just emerged from the other end of the trapdoor.
Kuzco turns back into a human and sets out to redeem himself, building Kuzcotopia on the hill next to Pacha's home.
Meanwhile, outdoorsman Kronk becomes a scout leader with the help of Bucky, and Yzma, now a cat, is sentenced to the tortue of being taught squirrel language by Kronk as a Junior Chipmunk.
In the spinoff, The Emperor's New School, Yzma once again plots to take the throne from Kuzco. The show's premise is that Kuzco must attend school and pass all of his classes in order to remain Emperor. If he fails even one class, he will not be able to retake the throne. In order to make Kuzco fail, Yzma poses as Principal Amzy, the principal of Kuzco Academy. With the assistance of Kronk, she comes up with various schemes (most involve potions that transform Kuzco into an animal, similarly to the film) in order to make Kuzco fail one of his classes. Several episodes reveal members of Yzma's family, including her mother Amza who, according to Yzma, nags her incessantly, forcing Yzma to carry out her plots. Yzma also apparently has siblings, as she has two nephews: Zim and Zam.
Role in the Series
Yzma is one of the Villain League's main potion-makers, and also has the ability to transform into a clone of the Terror Bird from Turok the son of stone, due to Scroopfan's perference of heroic cats and wasn't much of a fan for evil cats. Yzma is set to return in future projects.