One of the most successful concepts for the "mystery" books, as they were termed at the time, The Witching Hour made its debut with the Feb/March 1969 issue, and a great Nick Cardy cover.
There were framing pages at the beginning and end of the issue, introducing the Three Witches, Mildred, Mordred and Cynthia. In each issue, they would each introduce one story, and the readers were asked to vote on which told the scariest tale. Alex Toth does the art on the framing sequence, bringing to life the three very different witches.
The triad fit into the classical pattern, Maiden, Mother and Crone. Cynthia, the youngest, looks very un-witchlike compared to the others, at least at first, though as the years went by, her costume became more dated, and therefore more evocative. In the intro, each is ascribed as telling a different kind of horror story, although this was fairly loose, and the concept would not be maintained at all going forward.
Mildred relates the first story, by Denny O'Neil and Pat Boyette, which deals with an aging millionaire, and former dancer, who spends his vast fortune on a time viewer, and time machine.
He sees what looks to be some eternal dancing machine, and despite his scientists' protests of uncertainly, plunges through the time machine to get there. He winds up in the dancing machine, only to discover that it is actually a futuristic form of execution.
Toth does the art on Mordred's story, which is set in a European village, and deals with a man tormented by the townsfolk and chased up into their clock tower.
Over the years he seems to kill his tormentors, although at the end, when people finally venture up, they discover his body long dead, and those who drove him into the clock all turned to brass. The story doesn't make a whole lot of sense, but looks great.
Jack Sparling does the art on Cynthia's tale, which deals with an obsessive surfer and his doting girlfriend.
He hears about a private beach with a perfect wave, and is given a special surfboard by a witch. The surfboard creates a wave that carries him out into the ocean, and the girlfriend follows him to his doom.
In most issue the Three Witches will only appear on the splash page, and in narrative panels in the stories ascribed to them. I will be jumping over most of this series. Probably pretty much all of it. Stopping only on whatever issues I find that have stories which actually integrate the Three Witches into them.