Unlike other villains of the Batman series, she didn't commit crime for personal profit, but to pay her ally, Eivol Ekdol to make her annual escape device. Otherwise she made her living as a magician. She was known for being clever and being able to keep up with Batman during her only appearances.
Every year on April Fools' Day, Zelda would rob a bank of exactly $100,000 to pay Eivol Ekdol of her annual big escape trap. After two years on the case, Commissioner Gordon called in Batman and Robin to solve the case. With virtually no leads, thanks to Zelda's careful planning, Batman decided to make one by planting a pair of phony stories.
The first was that the money the Bank Bandit had stolen was counterfeit that was in the vault awaiting transport to be disposed. The other was that a rare emerald would be on display at Stonewall's Jewelry for one day only, it's value was $100,000. While Zelda and Eivol believed the story about the counterfeit money, Zelda saw through the other one saying it was too convenient a target. A quick scouting trip confirmed her suspicions. As a result before stealing the emerald, just to taunt the dynamic duo, she arranges the kidnap of Aunt Harriet for the necessary money.
As Aunt Harriet is lured outside to meet the special taxi, she is startled as two additional men appear into the back of the taxi with her. They each hold Aunt Harriet firm between them while they render her unconscious with a chloroform rag. The men are quite excited watching her eyes get heavy as she slowly passes out from the sedative. On their way to Zelda, the men encase Aunt Harriet inside a black nylon straitjacket, gag her with a thick terrycloth, and cover her face with a green silk scarf. Once there, Aunt Harriet is dragged inside to the vat. Zelda has them attach Aunt Harriet to a cable. She is hoisted in the air to dangle over a vat of boiling oil. As the heat starts to rise, it wakes Aunt Harriet. She kicked her feet in a frenzy from the overwhelming heat.
Zelda sat in her chair knitting. Watching television. She would glance over at Aunt Harriet now and again. Smiling to the sounds of her moaning through her gag. Zelda heard a thud and watched as Aunt Harriets' repeated kicking caused her shoes to fall from her nylon covered feet. The first shoe hitting the wall. The other into the boiling oil. Aunt Harriet would bend her knees to keep her exposed sheer pantyhosed feet from the heat. If Zelda's demands are not met, she plans to release the cable and drop Aunt Harriet into the vat of boiling oil!
Zelda finds out the money is real and promptly releases Aunt Harriet. Zelda ends up falling in love with Batman and saves him and Robin from Ekdal's trap. Ekdal had two criminals hiding in wooden caskets with machine guns preparing to kill Batman and Robin. Zelda warns them, saving the Dynamic Duo.
Ekdal tries to escape, but is captured with a Batarang and Zelda with tears in her eyes, allowed herself to be arrested. Later in prison, she was visited by Bruce Wayne who said because she saved the Dynamic Duo, she would be have a job as top lady magician, performing for the children's hospitals after she finished serving her time. Zelda was very grateful and presented Bruce with a flower to give to Batman as a thank you.
- Eivol Ekdal (portrayed by Jack Kruschen) - A strange Albanian genius who made the various escape devices for Zelda each year for the price of $100,000. Unlike Zelda, Eivol was truly crooked and his high prices were the reason she had taken up crime.
- Hood no.1 (portrayed by Victor French) - Zelda the Great's henchman
- Hood no.2 (portrayed by William Phipps) - Zelda the Great's henchman
- While Zelda never appeared again, Anne Baxter did in season 3 as Olga, Queen of Cossacks. This marked her as the only guest actor to play two different villains.