One of my favourite books as a child was The Sword in the Stone. Not the original by T. H. White, but a little book based on the 1963 Disney animation. It was basically a truncated retelling of the story illustrated with stills from the film. I loved the whole thing, but especially the character of Madam Mim.
I always admired how she had purple hair and could turn into animals. Both things I aspired to at the time.
For whatever reason she popped into my head the other day. Possibly while I was doing something eccentric. Wish I still had that book, but I'm pretty sure it fell apart from being read so much.
I still think it would be cool to be Madam Mim.