I hesitate entering into this territory because it can start to look political and I don't want to hijack the light hearted intentions of this poll or to create the basis for a potentially contentious discussion.
But, generally, the word wizard is used for men. The comparable word, in a way, for women is witch.
Whereas wizard often means someone wise and powerful, the name/label witch has - culturally and colloquially - a more sinister and ugly context on it.
There are a lot of reasons for this and it's complicated, but I think it's evidence of a long history of bias against women having power. Especially power that the average male might not have.
The list that DanielLB provided - I would wager (without checking them all) - are all/mostly witches. And there is a wikipedia page for lists of witches but not a comparable one of wizards that could let us check which female characters might be called a wizard.
If we asked people - quick - to name the first 5 wizards that came to mind, I bet all would be characters we would consider 'good'. If we asked people to do the same with witches, I'm not so sure we'd get 'good' characters.
I don't try to get too political with pop culture. Pop culture, for the most part, serves to entertain and we allow ourselves to set aside some standards to do that (otherwise, how could we 'enjoy' violent movies, for example).
But pop culture is rooted in history. Both in history that happened (like the Salem witch trials) and history of what what functioned as contemporary culture throughout different eras and ages.
And pop culture perpetuates stereotypes and beliefs and biases. The way we look at magical, powerful men is quite different from the way we look at magical, powerful women. If we call someone a witch, it's almost always a pejorative. One that is completely gender based.
So, I'm looking forward to voting on my favorite witch but I'm eager to see what list is presented and whether the characters are as likeable as the wizard list (I hope it's not a list of only HP characters). And I had a little moment of dismay when I realized that this poll would be male only. This is a list of intriguing and powerful and commanding people. But women couldn't be part of it. I don't take any offense at the poll in any manner. It's just a personal sigh moment.
It also made me think of four young women I used to teach. I'm going to call them young women even though they were in first grade. They were bright and quick and intelligent and humorous. I was reading books about pumpkins, and talked about jack o'lanterns. They, amongst themselves, started calling them jill o'lanterns. That just tickled me to no end. They took one of many gender specific titles and made it something they could relate to. :-)
and... just in case it looks like I was boycotting this poll, I wasn't, really. It's just that my favorite wizard is really the persona of Merlin. Not the depiction of Merlin but the actual root of who this person might have been. (since I've done some reading on this) I enjoy many depictions of him but my favorite would be the potential 'man' himself. My favorite depiction.. or perhaps the one of which I'm most fond... is the one that appears in the Mary Stewart books. I also like the whole Arthur/Merlin/etc stories as told in Mists of Avalon.
It took me a bit, but I can name a handful "good" female witches from the media I'm familiar with:
-Willow from Buffy the Vampire Slayer -The sisters Halliwell from Charmed -The Good Witch from the Wizard of Oz -Serafina Pekkala from the His Dark Materials trilogy -Hermione Granger of Harry Potter -Kiki of Kiki's Delivery Service -Mary Poppins
In actual fact, Ian McKellen was offered the role of Dumbledore
[In reply to]
He turned it down for two reasons: 1. Because he had already played Gandalf and 2. Because one of the last things that Richard Harris did publicly was state what a dreadful actor he thought McKellen was, so Ian thought it inappropriate to take over his role.
she's the Morrigan, the Triple Goddess, and Gawain is her knight, the noblest in the land. Over about six centuries they both devolve, the Morrigan into a witch (although Morgan le Fey means "Morgan the Fairy") and Gawain into a drunken lout and rapist, who is replaced by the pure Christian Galahad who has nothing to do with women.