A Witch Should Never Be Without Their Hat...

 The MGM film with Judy Garland really screwed up the narrative. In the Oz books by L. Frank Baum, Glinda is the Good Witch of The South, not the north; the Good Witch of The North is Locasta, unnamed in the books, but given that name by Baum when he adapted it for the stage; when Ruth Plumly Thompson continued the series after Baum's death, she gave that character the name Tattypoo, which sounds like the name of a mixed toy dog breed. I prefer Locasta. 

 Baum would also revise Glinda a bit as the books went on - instead of a witch, she was more-often identified as a sorceress; in his essay, "Why Gandalf Never Married", Terry Pratchett regarded a Sorceress as "..just a better class of witch," followed by "An Enchantress is just a witch with great legs." 

 And then there's Wicked, which hints that Glinda is more of a fraud, neither witch nor sorceress, but someone who is given a title - Glinda the Good.

 At least they gave her a neat hat to wear..

 Oh, wait..

I can't find any insight as to why Glinda wears a pointed hat in the poster for the musical, but in neither the musical or the film adaptation of the musical does it appear as part of her wardrobe.

 Instead, Glinda wears a tiara.

    Even the film doesn't give her

                      a hat.

  So..I'll use some A.I. magic to give Glinda a pointed hat:

           Bibbidy, Bobbidy-Boo

 As a bonus, I'll use A.I. to fancast Locasta..the following is the best result I got from suggesting Linda Cardellini in the prompt:

    I believe the A.i. got tripped-up

    by the quirks of a certain facial       feature Linda has and wound-up

    adding more lines along the            face and neckline...

 A witch's hat is like a cowboy hat - it's part of their iconography. While it's true that Glida never wore a pointed hat in the books - rather, a crown with elements of a top hat and tiara - I liked the idea of her wearing a witch's pointed hat better.