Jonadab is a biblical figure mentioned in the Old Testament, specifically in the books of 2 Samuel and 1 Chronicles. He is known as the son of Shimeah and a cousin of Amnon, the son of King David. Jonadab is recognized for his cunning advice, particularly in the context of Amnon's tragic relationship with his half-sister Tamar. In the narrative, Jonadab plays a pivotal role by suggesting a deceptive plan that leads to the assault of Tamar by Amnon. This act sets off a chain of events that results in significant family strife and tragedy within the royal household of David. Jonadab's actions highlight themes of manipulation and moral failure in the biblical story.