Misuse case diagrams are a type of diagram used in application threat modeling that includes malicious users (also known as threat actors) and describes how their potential actions could threaten the system, as well as how the system mitigates those threats. These diagrams are an adaptation of use case diagrams, which are commonly used in software engineering to specify the required usages of a system. Misuse case diagrams, on the other hand, focus on the negative scenarios, illustrating how a system can be used improperly and what measures are in place to prevent or mitigate these actions12.

References: The explanation utilizes the knowledge of misuse case diagrams as a tool in threat modeling to understand and communicate about potential security threats12.