Tutankhamun's mummy
Detective Michael R. King and FBI profiler Gregory M. Cooper came together with an actual Egyptologist to form their own theory which was that Tutankhamun was murdered. With the use of forensic evidence and their extensive backgrounds in criminology, they came to the conclusion that he was likely murdered by one of his closest advisors, Ay. Ay did succeed Tutankhamun on the throne, so they used that as the motivation for the murder.
Nakhtmin
He was the heir to the throne during the reign of the pharaoh Ay though he never became a pharaoh. It is assumed by scholars that he died towards the end of the reign of Ay (when he seemingly vanished from all records) and Horemheb, the designated heir of Tutankhamun, became pharaoh instead.