Since the discovery of Tutankhamun's mummy, there has been a lot of speculation and theories on the exact cause of death, which until recent studies had been hard to prove with the evidence and data available. While it was a widely debated topic for many Egyptologists, it had also spread to the general public as popular culture has come up with many conspiracy theories that played out in movies, TV shows, and fictional books. Author James Patterson has even recently written his own take in his book, The Murder of King Tut. There are many educated and respected Egyptologists as well as trained professionals in other fields who have devoted a lot of time researching Tutankhamun and who have varying beliefs to his cause of death. Some have stood by their theories even in light of new evidence. Some of the theories are better known and supported than others. 

 The initial examination of the mummy reported the body showed "no traces of the cause or causes of the young king's death."  Bone fragments seen inside the skull in the 1960s x-rays led Harrison to propose that Tutankhamun died from a blow to the head. This has led to "endless speculation as to whether (or how) the king was brutally attacked or murdered", with Tutankhamun's vizier Ay considered the most likely culprit as he stood to gain the most from the young king's early death and ultimately succeeded him as pharaoh.  It is now known that they are a result of the mummy's modern unwrapping as the fragments are loose inside the skull and there is no evidence of bone thinning or calcified membranes indicative of a fatal blow to the head.  Death as a result of a brain tumor was also not supported by anatomical studies. 


The most recent CT study lead by Hawass has attributed Tutankhamun's early death to a combination of multiple factors including a leg fracture and malaria. The fracture of the left leg has resin within it, indicating an associated open wound was present at the time of death. They suggest that the fracture was the result of a fall, and turned fatal either through infection or in combination with a severe malarial infection. However, Christian Timmann and Christian Meyer have argued that sickle cell anemia better fits the pathologies exhibited by the king. They suggest that the sickle-cell disease turned fatal when Tutankhamun also contracted severe malaria. He is expected to have been homozygous recessive for the sickle cell gene, thus making him not immune to severe malaria, which would have been fatal.  This suggestion has been called "interesting and plausible" by the Egyptian team.