The Spanish Tragedy, highly influential and popular in its time, established a new genre in English theatre - the revenge play or revenge tragedy. The plot of ""The Spanish Tragedy"" contains several violent murders and includes as one of its characters a personification of Revenge. This work was often referenced in works written by other Elizabethan playwrights, including William Shakespeare, Ben Jonson, and Christopher Marlowe. Many elements of The Spanish Tragedy, such as the play-within-a-play appear in Shakespeare's Hamlet. Thomas Kyd is also frequently proposed as the author of the lost Ur-Hamlet play that was one of Shakespeare's primary sources for Hamlet)