Duke of Vienna (Friar Lodowick)- the Duke decides to leave the running of his country to one of his citizens then disguises himself to see the outcome.  When one of his subjects is to be executed, the Duke dressed as a Friar decides to interfere.  At the end of the play he decides to deal out justice to the subjects who have wronged. 

Angelo- he subject with whom the Duke leaves the running of the country.  While trying to follow all of the laws strictly, he lusts after Isabella and in turn breaks the law himself.  Because of his lust, he becomes wrapped up in the Duke's plans and ends up sleeping with his ex-fiancée, Marianna.

Claudio- a man sentenced to death because he had sex with the woman he loved, Juliet.  He wants his sister, Isabella, to sleep with Angelo to pay for his freedom. 

Escalus- a judge who helps Angelo make the executive decisions while the Duke is away.

Isabella- the sister of Claudio who wants to become a nun.  She pleads with Angelo for her brother's life, but is appalled by the offer he makes her.  She gets wrapped up in the Duke's plan, and later has him propose to her. 

Mariane- the former fiancée of Angelo who he rejected because of a lost dowry.  The Duke in disguise has her sleep with him, pretending to be Isabella, in order to trap him into marriage. 

Barnadine- a prisoner with Claudio who is supposed to be executed.

Abhorson- the executioner who has Pompey as an apprentice.

Lucio- a friend of Claudio who convinces Isabella to plead for him. He also offends the Duke by unknowingly slandering him. 

Varrius- a friend of the Duke

Juliet- the fiancée to Claudio.

Friar Peter and Friar Thomas- men who help the Duke in his plans.