The three witches, or weird sisters, despite appearing only briefly in four scenes in the play are some of the most important and memorable characters in William Shakespeare's play Macbeth. They serve several important functions in the development of the plot. First, they are evil, and Macbeth`s willingness to consort with them gives us an early sense that his ambition will overcome his ethical scruples. Second, their prophecies help motivate Macbeth to perform evil deeds. Third, their prophecies bring suspense and foreboding to the atmosphere of the play. Finally, they have wonderful poetic lines, and are great roles for actors!
the witches were the one leading macbeth and forcing him to go for the war and for this they were a very major character. They also were the ones who started the story because they were forcing all bad stuff to happen to the world