Glinda in the 1939 movie: More Locasta than Glinda?
It's common knowledge to Oz fans that Glinda the Good Witch of the North in the most famous movie (and subsequently most adaptations that reference it) is a composite of the books' Glinda the Good Witch of the South and the originally unnamed Good Witch of the North (named Locasta or Tattypoo depending on which Royal Historian you look to).
I recently read a comment that described the movie's Glinda as fairy godmother rather than regal sorceress, and it clicked that that's the vibe I get from GWN/Locasta/Tattypoo. She gives comfort and advice that's somewhat cryptic but turns out for the best, showing up when Dorothy needs her. The 1902 musical, which gave her the name Locasta, also has her show up to help Dorothy at all the same times that Glinda does in the movie: on arrival, sending snow to wake her from the poppy field, and at the end to send her back to Kansas when all seems lost.