Graymalkin and Paddock are deemed evil spiritual entities who summon the Witches after their first meeting with Macbeth, who was accompanied by Banquo. They are not characters within the play with dialogue, but reference to as a higher authority than the Witches, and by the Witches themselves within their dialogue.
An instrumental device of Shakespeare's to acknowledge their spirtual existence without having to include them in the cast of characters.
