Tybalt plays the role of the excitable cousin of Juliet in the play Romeo and Juliet. He is actually the spark that sets off the explosion that forces Romeo to flee Verona and eventually leads to the death of the two main characters.
Early in the play, after Romeo and Juliet have met, Tybalt and other Capulets encounter Mercutio and other Montagues. Due to their age-old feud, these characters have a hard time simply letting each other pass by without picking a fight. At this point, Tybalt and Mercutio engage in sword play, with Tybalt killing Mercutio as Romeo attempts to intervene and keep the peace. Romeo in turn, fights Tybalt and kills him, thereby destroying any hope of a reconciliation that will make his relationship with Juliet a future possibility.