Themes in Hamlet

Disease and Poison.
"Something is rotten in the state of Denmark" is only one of many such images and references.
Indirections. (Appearance and Reality).
This category is named after Polonius' statement that he can "by indirections find directions out." What all these entries have in common is that they speak of something hidden, which emerges, or is discovered, or is almost--but not quite--revealed.
Fortune, Fate, and Providence.
What is the name and nature of those powers beyond our power? Is everything just a matter of luck, or is there some great plan?
Revenge.
In a traditional revenge tragedy, such as Shakespeare's Titus Andronicus, the hero plans his revenge so that it is surprising, sudden, and very bloody. This play is different.
Weeds and Flowers.
Ophelia's flowers are famous, but the play has plenty of weeds, too.
Frailty.
When he thinks about how his mother has changed from a grieving widow to the bride of his hated uncle, Hamlet exclaims, "Frailty thy name is woman!" This is the first of many comments, by Hamlet and others, about the sometimes mysterious ways in which people change.
Suicide.
Hamlet twice contemplates suicide; a gravedigger is of the opinion that Ophelia probably committed suicide; a priest is sure that she did; and Hamlet spends his last words talking Horatio out of killing himself.