movie - Is there a Good Witch of the South?

In the Wizard of Oz (the movie version) the Good Witch of the North, Wicked Witch of the West and Wicked Witch of the East are all mentioned.

Was there ever a Witch of the South?

Answer

If you are talking about the 1939 film, no Witch of the South is mentioned. I searched the movie script online and no instance of "south" was found. In the film, Glinda is the Good Witch of the North. In the book, Glinda is the Good Witch of the South. In the film, Glinda performs the functions which the book's Good Witch of the North performed.

In the 1939 film version of The Wizard of Oz, Glinda is the Good Witch of the North, not the South as in the book. She is played in the film by Billie Burke. Glinda performs the functions of not only the novel's Good Witch of the North and Good Witch of the South, but also the novel's Queen of Field Mice, by being the one who welcomes Dorothy to Oz, sends her "off to see the Wizard," and orchestrates her rescue from the deadly poppy field in addition to revealing the secret to going back home.

Source: Wikipedia

If you are talking about the books, Glinda is the Good Witch of the South. There is a Good Witch of the North, but she is not very fleshed out.

She appears in Chapter 2. The Council with the Munchkins.

A description of her appearance:

Three were men and one a woman, and all were oddly dressed. They wore round hats that rose to a small point a foot above their heads, with little bells around the brims that tinkled sweetly as they moved. The hats of the men were blue; the little woman's hat was white, and she wore a white gown that hung in pleats from her shoulders. Over it were sprinkled little stars that glistened in the sun like diamonds. ... But the little woman was doubtless much older. Her face was covered with wrinkles, her hair was nearly white, and she walked rather stiffly.

Explaining the existence of the four witches:

"But I thought all witches were wicked," said the girl, who was half frightened at facing a real witch. "Oh, no, that is a great mistake. There were only four witches in all the Land of Oz, and two of them, those who live in the North and the South, are good witches. I know this is true, for I am one of them myself, and cannot be mistaken. Those who dwelt in the East and the West were, indeed, wicked witches; but now that you have killed one of them, there is but one Wicked Witch in all the Land of Oz--the one who lives in the West."

Source

Here is a 1900 illustration of the Witch of the North from the book:

Wikipedia has this to say about her:

The Good Witch of the North is a fictional character in the Land of Oz, created by American author L. Frank Baum. She is the elderly and mild-mannered Ruler of the Gillikin Country. Her only significant appearance in Baum's work is in Chapter 2 of The Wonderful Wizard of Oz (1900), in which she introduces Dorothy to Oz and sends her to meet the Wizard, after placing a protective kiss on her forehead. She makes a brief cameo appearance at Princess Ozma's birthday party in The Road to Oz (1909), but is otherwise only mentioned elsewhere in the series.