Critically speaking, The Duchess of Malfi is considered to be a Jacobean era (1603-1625) revenge play, or revenge tragedy. In writing The Duchess of Malfi, Webster borrowed elements form other sources including William Painter and Sir Philip Sydney. He incorporated selected elements of revenge tragedy tradition but adopted them to accommodate his theme and dramatic purpose.
Elements of revenge tragedy are:
1. A secret murder of a good leader by a bad person.
2. The visitation of the victim's ghost to someone like a son.
3. Scheming and plotting with disguise and intrigue conducted by both avenger (revenge taker) and murderer.
4. Dead bodies slowly increasing in number.
5. The avenger falls into madness, either real or pretended (feigned), or another character does.
6. Mass violence of some sort in the resolution.
7. A final catastrophe that ends in the avenger's own death.