Theme #1) Madbess is one of the main themes it Hamlet. Hamlet shows many many parts of his personality since the death of his father, he is shown as a mentally disturbed person.
Theme #2) Subversion of Relationships. There are many twists of relationships and such shown in Hamlet. For instance the situation where Gertrude is a cousin of Claudius and must not marry him in legal or religious terms. However, they both marry changing their relationship. Claudius is Hamlets uncle but also becomes his step father.