Balthasar is Romeo's servant and trusted friend. While he is not directly referenced in the first scene of the play, the directions call for two Montague servants to quarrel with Sampson and Gregory. He then comes back in Act V Scene 1 telling Romeo about Juliet's death. In the last scene (Act 5 Scene 3) in the graveyard, he tries to stop Romeo from entering the vault but he gives up and lets him go into the tomb. Romeo gives him money saying that he is a good friend and then he hides in the graveyard despite Romeo telling him not to. Later Friar Laurence runs past Balthasar and asks him where Romeo is and Balthasar tells him that he is inside the tomb. Then the Prince calls him in and asks him questions about why was he there. He gives the Prince the letter that explains why Romeo killed himself.
