Most of its theme, structure and language comes from The Spanish Tragedy by Thomas Kyd.

In Kyd's The Spanish Tragedy, there are several graphic murders, and the protagonist bites out his own tongue.

Thomas Kyd's The Spanish Tragedy, however, is the first major example of the revenge plot in English drama.

He remembered a curiously apposite echo of a line from Kyd's Spanish Tragedy.

Bel-imperia is a character in Thomas Kyd's The Spanish Tragedy.

In his critique of the Spanish Tragedy, he points out that mercy is a word which is not used once throughout the play.

Thomas Kyd's The Spanish Tragedy (1582-1591) may also have served as a minor influence.

The Spanish Tragedy was enormously influential, and references and allusions to it abound in the literature of its era.

An additional theme of The Spanish Tragedy is tragedy itself, or more specifically murder and death.

The Spanish Tragedy is no different.