Yzma (pronounced /ˈiːzma/) is Kuzco's advisor and the primary antagonist of the series. In the English version, she was voiced by Eartha Kitt since her first appearance until Kitt's death.
Yzma's character in the series is seen to be malicious, but comically eccentric, often calling herself beautiful even though all other characters in the series consider her appearance "scary beyond all reason". She is intelligent and comes up with grandiose plans and schemes with a set objective in mind, but fails to pay attention to the minor details of it. More often than not it causes the scheme to backfire on her. Yzma is seen to have some knowledge in chemistry, as she accidentally uses extract of llama on Kuzco, thinking that it was poison. Kronk in the first film states that she should re-label her potions, because everything she makes in her "secret lab" has the exact same pinkish color. It is suggested that Yzma can use magic, however, this is never shown. She is portrayed as more of an alchemist, though claims to be a sorceress.
Originally serving as the Emperor Kuzco's advisor, she is later fired after meddling in his affairs and attempting to act as Empress in his absence. Enraged at her banishment, Yzma conspires with her dim-witted assistant Kronk to dispose of Kuzco. The two head to the "secret lab" -- which apparently everybody already knows about—to concoct a plan to kill Kuzco. The film producers have stated that she is a complicated thinker; an example given with her original plan to kill Emperor Kuzco. The plan involved her turning him into a flea, putting him in a box, putting that box into another box and then mailing that box to herself only to smash it with a hammer. But after thinking it over (and partially because she knocked over some poison onto a plant), she decides to save on postage and simply poison him. The concept of her formulating a nonsensical plan before settling on an easier-to-pull-off idea (always a potion) would later be used as a running gag on the series.
Yzma also appears in the direct-to-DVD sequel Kronk's New Groove, in which she has returned to human form but still has the tail of a cat. During the first half of the film, she sells sewer sludge to the old people, telling them that it is a youth potion, but once Kronk finds out her potion is a fake, the old people chase her down, where she uses a potion to transform herself into a rabbit, to prevent them from attacking her. She is then snatched and carried away by a falcon. At the end of the movie, in a nest just outside the restaurant, she is presumably eaten by the falcon's chicks right after they hatch.
In The Emperor's New School, Yzma constantly plots to get Kuzco to fail his classes at Kuzco Academy, allowing her to become empress; to this end, she poses as Amzy, the principal of Kuzco Academy. Her plans mainly consist of transforming Kuzco into different animals to thwart his attempts to pass a class, though they often work to his advantage. In the episode "Monster Masquerade", Yzma takes a cobra form similar to Jafar's from the Classic Disney film Aladdin. Yzma possesses many of Kuzco's more negative traits including impatience, selfishness and vanity. Some of Yzma's known relatives appear at times in the series. They include her twin nephews, Zim and Zam, (voiced by Dylan and Cole Sprouse) who appear in Chipmunky Business, and her mother Azma, (voiced by Ellen Albertini Dow) who appears in The Bride of Kuzco and looks just as ancient looking as Yzma (possibly even more so) and converses by sighs and chuckles. In one episode, Yzma remarks that her plots to destroy Kuzco are primarily due to her mother constantly nagging her. A running gag throughout the show is that Yzma is often referred to as, and mistaken for, a dinosaur. She sings your favourite disney villain song called Snuff out the light from The emperor's new groove.