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.
Mummy (monster)
The original inspiration for undead mummies comes from the process of mummification.
During the 20th century, horror films and other mass media popularized the notion of a curse associated with mummies ("see Curse of the pharaohs"). The 1922 discovery of Tutankhamun's tomb by archaeologist Howard Carter brought mummies into the mainstream.