Easily Egypt's most famous pharoah, Tutankhamun actually accomplished very little in his reign. In fact, for most of it he was a puppet of his advisors. So why is he so well known? Simple. He had a big advantage over every other discovered pharoah. He had the historical equivalent of finding Big Foot. He had an unplundered tomb.
Practically every Egyptian tomb discovered was partly or completly plundered. Because his tomb wasn't, it was remarkable to see all the richness of the ancient world, something which captured the public's imagination.
So who was Tutankhamun? He ruled for nine years, starting at only nine years old. His father was a fanatical relgious reformer who reduced the priests' power. However Tut restored their wealth, possibly at his the behest of his advisors. He managed to restore realtionships with other countries his father had messed up. Compared to his father at least, he was a good king.
There are no records of King Tutankhamun's last days. What caused his demise has been the subject of several disagreements. Studies have been taken in an attempt to find out the cause of death. There is some evidence, advanced by a microbiologist, that his burial may have been rushed. The theory that was put forward was that dark brown splotches on the decorated walls of Tutankhamun's burial chamber suggested that he had been entombed even before the paint had a chance to dry.
While many think Tut's death was an assination, it was probably caused by malaria and an infected broken leg.