Margaret Hamilton, swooped down onto Sesame Street on February 10, 1976 guest starring as the Wicked Witch of the West.
She dropped her broom presumably in flight over the small town where David retrieved it from the street. David did not want the broom returned to her, fearing the trouble it could cause.
Hunting for her broom, she visited Mr. Hooper’s store where she made it rain inside – after being offered a coffee. Big Bird had been threatened to be turned into a feather duster.
However, children at home didn’t seem as pleased with the Witch, nor did parents:
This episode prompted an unusually large amount of mail responses from parents, almost entirely negative, within a short time frame. Typical responses included parents concerned that their children were afraid and now refused to watch the show, using such phrases as “screams and tears” and “the threat of the witch’s power remains in children’s eyes.” A somewhat atypical missive came from a self-proclaimed Wiccan, concerned with the perpetuation of a negative fairy tale stereotype and recommended a segment “portraying witches as they really are, now.”  – Muppet Wiki
The Witch tried with all her might to retrieve her broom, but when the mean threats didn’t work – incognito as a friendly, old lady! It was the episode’s intent to teach “the value of planning by creating and implementing methods of retrieving the broom.”
In turn, children became test subjects:
Due to the overwhelming reaction, additional test screenings were held from March 1 through the 5th, “to assess children’s reactions to the Wicked Witch of the West.” The tests showed that children were “exceptionally attentive during the Margaret Hamilton segments,” and those who watched the episode in color were fascinated by her green face. The issue of fear was difficult to fully judge, due to confusing answers and the fact that the children were surrounded by their peers and adults, and not alone watching. However, due to the parents’ reactions, the letter content and testing observations, Anna Herera of the CTW Research Department suggested “that the Margaret Hamilton show not be re-run.”  – Muppet Wiki
Oscar the Grouch, on the other hand, took a shine to the Witch leaving some feeling he may have become smitten with her. Even the big yellow fellow took a liking to her and seemed slightly depressed when she took-off back to her castle.
Could you imagine if all we had left of the classic film “The Wizard Of Oz”, were a few polaroid pictures of the Tin Woodman, Scarecrow, Cowardly Lion, Dorothy and her dog Toto?
– altered by Hystoria