Agatha Cackle

Agatha Cackle is a major antagonist of the children's book series'' The Worst Witch. ''She's Amelia's evil twin sister who wants to take over the Cackle's Academy.

Appearance
She and Amelia look almost similar in appearance (considering they're twins),they're both short, and wear gray, but Agatha has glasses that are large and round.

The Worst Witch
In Mildred's first year, on Halloween, Mildred spots her and her coven plotting to turn the whole academy into frogs.

In a flash of fear, Mildred turns both Agatha and her coven into snails and puts them in the boxes meant for the frog-pupils and frog-teachers and takes them up to the academy to show to Miss Cackle; Miss Cackle and Miss Hardbroom then deal with the witches.

The Worst Witch Saves The Day
Agatha reappears in Mildred's third year, where she sneaked into the school disguised as a new teacher, Miss Granite, with a high-pitched, squeaky voice, a huge cloud of orange curls, and an extremely bizarre personality. She is later found out by Mildred when Mildred comes to collect Tabby from her. Luckily, Mildred and her friends turn Agatha and her coven into snails themselves. While disguised as Miss Granite, Agatha is able to appear and disappear HB-style.

1998 Series
In Mildred's first year, on Halloween, Mildred spots her and her coven plotting to turn the whole academy into frogs.

One of Agatha's first instructions was to "Get Hardbroom" noting that she was the one they needed to get first because of her power. Mildred ends up shrinking the witches and handing them to Miss Cackle.

At the end of Mildred's First year, Agatha Sneaked into the Academy disguised as Miss Cackle[4], Mildred and company, however, realise that it is not Miss Cackle, but Agatha back to cause more trouble.

The girls track down the real Miss Cackle to the store cupboard in which Mildred and Enid were once trapped. Unfortunately, they are discovered by Agatha's two wicked cronies, Millicent Coldstone and Betty Bindweed. Mildred puffifies them and saves the day, for which she earns a raise in her final grade from C- to A+.