How did Shakespeare display Banquo's ghost in the original play Macbeth?

First of all, your question assumes that Shakespeare held a position in the King's Men similar to a modern director and that he made decisions about how plays should be performed. We have no evidence that he performed such a function or even that anyone did. The leader of the company was the star actor Richard Burbage, and if anyone made decisions of this kind it would be him. But in the portrayal of ghosts, the company probably did what they had previously done to portray ghosts in plays such as Richard III, Julius Caesar and Hamlet, and what they had seen done in many other Elizabethan plays such as The Spanish Tragedy or Thomas of Woodstock.We have an account of an early performance of Macbeth by the King's Men which describes this scene, as follows (the spelling has been modernised):

  • The next night being at supper with his noblemen, whom he had bid to a feast (to the which Banquo should have come), he began to speak of noble Banquo and to wish that he were there. And as he thus did, standing up to drink a carouse to him, the ghost of Banquo came and sat down in his chair behind him. And he turning about to sit down again saw the ghost of Banquo which fronted him so that he fell into a great passion of fear and fury, uttering many words about his murder, by which when they heard that Banquo was murdered they suspected Macbeth.

Clearly the ghost was visible to the audience, and could be seen entering the stage behind the back of the actor who played Macbeth. This set up a dramatic irony as Macbeth complains that Banquo has broken his promise to attend the feast, while the audience sees him sitting there. How did the audience know that it was a ghost? Again we must speculate. It cannot have been costume as the audience needed to know just by looking whose ghost it was, and costume is how they would have recognized the character. Perhaps white makeup was used.