"Who will I be today?"
—Lady Ev, trying on masks
Lady Ev is a ruler of the Kingdom of Ev. She's very fond of very elaborate masks.
In the world of Emerald City
Princess Langwidere, called Lady Ev, lost her mother at the very young age during the flood caused by the Beast Forever.
The kingdom of Ev is much more technologically advanced than Oz, it's soldiers using guns instead of swords.
Langwidere is first seen in episode four of the series when she enters Jane's workshop, seeking a new mask to wear.
She meets Jack, whom she taunts. Still, she becomes fascinated by him and orders Jane to give him to her, which she reluctantly does.
Langwidere, her father the king and Jack travel to Oz. They take part in a banquet, at which Langwidere behaves like a spoiled child. She later admits to the Wizard that she holds a grudge for Oz leaving Ev to drown when the Beast Forever came, thus dooming her mother.
The next day, Langwidere takes Jack to the fair. They are attacked in a back street and Jack fights off the assailants thanks to his metal body. Langwidere kisses him.
Langwidere is growing more impatient with her senile father. She is distraught, thought, when he is accidentally turned to stone by Silvie and vows to bathe Oz with blood. Strangely, she changes her mind having seen the Wizard kill Anna with a gun.
In the works of L. Frank Baum
Princess Langwidere, niece of king Evoldo, became the regent of the country once her uncle committed suicide. She's vain and self-absorbed, devoting just 10 minutes a day to the matters of the state.
She has about 30 different looking, but still extremely beautiful heads. She can chose which head to wear each day that best suits her mood. When Langwidere met Dorothy, she wanted to take the girls head to her collection, offering one of the less attractive heads instead. Dorothy was rescued by Princess Ozma.
Langwidere is portrayed as Chariot card from Tarot on the Emerald City Facebook page. Chariot means Victory, will, self-assertion and hard control.