This is an easy question to ask but a very difficult question to answer. To understand why it is so difficult to answer we need to know what happened after Tutankhamen died, and to understand what happened after he died we need to know what happened before he was born.
This also helps us to understand why Tutankhamen’s tomb was found almost intact whereas all the other Pharaohs’ tombs in the Valley of the Kings had been robbed of everything of value.
What follows here is a very simple possible reconstruction of the reigns of five Pharaohs, the last five Pharaohs of what Egyptologists call the Eighteenth Dynasty. (Historians divide Kings of England into Anglo Saxons, Normans, Plantagenets, Tudors etc in exactly the same way.)
Amenophis iii (about 1391 - about 1353)
The capital of Egypt was at Memphis, near modern Cairo. The site of Memphis is now buried under several metres of Nile mud. At the time of Amenophis iii the most important God in Egypt was Amun, and although the capital of Egypt was at Memphis the centre of the worship of Amun was several hundred kilometres south of Memphis, at a place called Thebes (modern Luxor), and the temple of Amun at Thebes was the largest temple in all Egypt.
Amenophis iii was the richest and most powerful Pharaoh in the whole of Ancient Egypt’s three thousand year history. He became King of Egypt when he was twelve years old, in about 1391 (BCE of course!). He reigned for thirty eight years and died at, for those days, the old age of fifty in 1353, and was buried in The Valley of The Kings.
Like most Pharaohs before and after him he built or enlarged temples to many of the Egyptian Gods, but he introduced a new style of building and a much more natural style of art, even allowing himself to be shown as fat and middle-aged!
Everything in Egypt was driven by two great natural forces, the Sun and the River Nile. Egypt is much nearer the Equator than England so the Sun is much brighter and hotter, and also there were no clouds in the sky in Ancient Egypt, so the Sun shone all day every day.
When the Sun first rose in the East it gave light but very little heat. But soon it began to give heat, and by mid-day the heat was unbearable. Then in the evening it was cooler, and finally the Sun went into the Earth. During the night the Egyptians believed the Sun passed through the Underworld, and in the morning it was reborn. The Sun God therefore took many forms and many names: Ra, Khepri, Atum, and the Aten, to name but some. Unlike the other forms of the Sun God, the Aten was visible to everybody as the Sun's disk. Amenophis iii did not neglect the temples or the worship of Amun and the other gods, but he personally had great devotion to the Aten, as had his father before him, and he built a new temple to it.
Every Pharaoh had to have a Great Royal Wife. The Great Royal Wife was very important and had lots of Royal duties, so often Pharaoh took a female relative, perhaps even his sister or daughter, to be Great Royal Wife. Most Pharaohs would also have had other, ordinary, less important, wives. Amenophis iii took as his Great Royal Wife a very beautiful woman called Tiy. Unusually she was a commoner.
Amenophis iii and Tiy had two sons. The first was named Tuthmosis and the second was was named Amenophis - it was the custom for a man to name his first son after his own father and his second son after himself.
Amenhophis, the second son, was born with a condition which meant his skull was egg-shaped, with a bulge at the back. He did not inherit this condition from his father (but he did pass it on to his children, including Tutankhamen).
Tuthmosis seems to have died before his father. After the death of Tuthmosis Tiy feared that Amenhophis might not become Pharaoh when his father died, so she arranged for him to be made co-regent while his father was still alive. A Pharaoh often appointed a co-regent to share the throne with him, either because he was getting old and could no longer rule by himself, or to make certain there could be no argument about who was to succeed him as Pharaoh when he died.
When a man became Pharaoh or co-regent he took new names, including a Throne Name. (In the same way a Pope takes a new name when he is elected.) From that moment on Pharaoh would be known only by these new names. Amenhophis iii's Throne Name was Nubmaatre, and Amenhophis his son took the Throne Name Neferkheperure when he became his father's co-regent. (Tutankhamen took the Throne Name Nebkheperure when he bcame Pharaoh.) Most books, other than the most specialised, on Ancient Egypt do not mention or give Throne Names because they are not usually helpful and can be confusing - I mention them here only because they are important for the next Paragraph.
Amenophis iv (Akhenaten) (about 1353 - about 1335)
Amenophis iv became Pharaoh (as co-regent) while his father was still alive and they ruled together for several years. His father had worshiped the Aten but had not neglected Amun and the other Gods of Egypt. But Amenophis iv worshiped only the Aten. He changed his name to Akhenaten, which means Light of the Aten, and built a completely new city in the desert, about half way between Memphis and Thebes, to be his capital. He called this city Akhetaten, which means the Horizon of the Aten. Today the site of this city is called by the Arabic name tell el Amarna, or just Amarna. Today it is a total ruin. Once he had moved into his new city he never left it again. This period of Egyptian history is usually called the Amarna period.
Isolating himself in this way from the rest of Egypt to devote himself to the worship of the Aten would have been fine if he had not been Pharaoh. But as Pharaoh he controlled all the wealth of the country, he was the head of the army and the navy, the farmers, the police, the schools, the foreign office, everything. He built a huge new Temple to the Aten in Akhetaten and closed all the other Temples to all the other Gods, and stripped all their priests of all their powers. While he was shut up in his city the rest of Egypt came almost to a standstill, the public buildings and granaries (food stores) fell into disrepair, and the people were brought to the brink of starvation.
Like his father before him he had several wives. His Great Royal Wife was a very beautiful woman called Nefertiti, and she bore Akhenaten several daughters. He also had a son by another wife, called Kiya, and he called this son Tutankhaten, which means the living image of the Aten. (Tutankhaten later changed his name to Tutankhamen).
Towards the end of Akenhaten’s reign Nefertiti “disappears” and at the same time a rather shadowy figure known as Smenkhare appears. Smenkhare is listed as Akhenaten’s successor. There are lots of theories about who Smenkhare was and what happened to Nefertiti, but many Egyptologists now believe that Akhenaten had made Nefertiti co-regent and that Smenkhare was one of the new names that she took when she became co-regent, and that she outlived her husband so was Pharaoh by herself for a short time. (The name Smenkhare could be male or female. There had been another female Pharaoh, called Hatshepsut, about a hundred and fifty years earlier.)
Tutankhamen (about 1333 - about 1323)
Tutankhaten came to the throne on the death of Nefertiti, when he was about nine years old. The whole country was in chaos after the reign of his father, and he very quickly started to put things right. He changed his name to Tutankhamen, which means the living image of Amun, and moved the capital back to Memphis. He rebuilt and extended the temple of Amun at Thebes, and restored the worship of all the other gods. He had two very able advisers, Ay and Horemheb, who had also served under Amenophis iii and Akhenaten. Ay was Nefertiti’s father.
When he became Pharaoh Tutankhamen took Ankhesenpaaten, one of the daughters of Nefertiti, as his Great Royal Wife, and she changed her name to Ankhesenamun at the same time that Tutankhamen changed his. There are the mummies of two tiny baby girls in Tutankhamen's tomb but for various reasons Egyptologists do not think that Tutankhamen and Ankhesesamun had any children, that these little mummies are not their daughters.
Tutankhamen died suddenly and very unexpectedly when he was about eighteen years old, after only about nine years on the throne. At the time of his death he and Ay were at Thebes and Horemheb was at Memphis. Tutankhamen had no children, but Ay was the father of Nefertiti and therefore the only person with even the slightest legitimate claim to the throne. Under Egyptian law the new Pharaoh could not actually be made Pharaoh until the old Pharaoh had been buried. Memphis was several hundred kilometres north of Thebes, and Ay buried Tutankhamen very secretly and quickly, so that by the time Horemheb heard about Tutankhamen’s death Ay had already buried him and had had made himself Pharaoh.
Because of the speed and secrecy with which Tutankhamen was buried many of the things in his tomb were intended for other people - even the second of his coffins had someone else’s face on it!
His sudden and unexpected death and the speed and secrecy of his burial has given rise to speculation that he was murdered, but there is no forensic or other evidence to support this viewpoint.
The murder theory was originated at the time it was believed that, because of his youth, for the first few years of his reign Tutankhamen was just a figurehead, and that the real power was wielded by Ay and Horemheb. When Tutankhamen was old enough to start wanting real power Horemheb and Ay saw him as a threat to their position, and one or the other of them disposed of him. In fact however it was by no means unusual for a young Pharaoh to take full power from the very start of his reign, and all the evidence suggests that this is exactly what Tutankhamen did do.
Usually the tomb of a Pharaoh, or even a commoner, would contain a lot of things, including papyri, which would tell us something about its owner. But because of the way in which Tutankhamen was buried the things found in his tomb tell us almost nothing about him. In particular no papyri were found.
To read more about Tutankhamen’s tomb please click here 
Ay was already an old man when he became Pharaoh, and reigned for only four years. He continued the work of restoration started by Tutankhamen. He was buried in The Valley of The Kings. After his death there was no one at all with any legitimate claim to the throne and so Horemheb made himself Pharaoh.
He even tried to destroy Tutankhamen’s tomb, but the Overseer in the Place of Truth (the man responsible for keeping the records of the location of all the tombs in the Valley of the Kings) told him he did not know where it was. Horemheb did however find and wreck Ay’s tomb. What happened to the tombs of Akhenaten, Nefertiti, Tiy and Kiya is described later.
For the next three thousand years it was as though Akhenaten, Nefertiti, Kiya, Tutankhamen and Ay had never existed. It is this destruction of so many of the contemporary records which has made reconstructing the history of this period so difficult.
On the other hand, Horemheb’s destruction of almost all the evidence for the life of Tutankhamen also destroyed almost all the evidence for his death and burial, and this in turn meant that within a few years of his burial the tomb robbers did not know where to find the tomb, or even of its existence, and so it survived almost intact for the next three thousand years.
Whatever some books may say, Horemheb’s vendetta was directed against Akhenaten and his family, Nefertiti, Kiya, Tutankhamen and Ay, not the worship of the Aten. The temple to the Aten at Akhetaten was destroyed only because it had been built by, and therefore included the names of, Akhenaten and Nefertiti. Other temples to the Aten were not damaged, and the Aten continued to be worshiped alongside Amun throughout the reigns of Horemheb and his successors.
Ma'at is often portrayed in Egyptian art as a beautiful young girl wearing nothing at all except a feather in her hair, and today she is often referred to as the Goddess of Truth, but to the Ancient Egyptians the concept of Ma'at ran far deeper than this. Ma'at was everything that kept Egypt from chaos, that ensured law and order, that protected her from her enemies and ensured her well-being, and Pharaoh was the defender of Ma'at. For this reason a crime against Pharaoh was a crime against Ma'at, and quite unthinkable to any Egyptian who loved and wanted to serve his country. All the evidence shows that Horemheb served Akenhaten, Nefertiti, Tutankhamen and Ay faithfully and loyally while they reigned; his vendetta against them did not start until he was Pharaoh and he himself had become the defender of Ma'at.
Akenhaten, Tiy, Nefertiti and Kiya all died in Akhetaten and were buried there, but after Tutankhamen restored the worship of Amun and the Old Gods he abandoned the city and moved their mummies to the Valley of The Kings, near to where he himself was to be buried. Just their mummies, not the gold and all the other treasures which would have been buried with them. But exactly where was not certain until very recently.
There are more than eighty tombs in The Valley of The Kings, and several more in another valley leading off it, known as The Western Valley.
Most tombs were robbed of all the gold and other treasure in them within a few years of them being made, but sand blows everywhere in The Valley of The Kings and most tombs were soon buried in sand again after they had been robbed. Over the next three thousand years people visited The Valley of The Kings and uncovered some of the tombs, but they not could understand what they found there because they could not read the hieroglyphs. Then in 1799 the Rosetta Stone was found. This contained the same decree written three times, in heiroglyphic, hieratic, and Greek. Comparing the Greek (which he could understand) with the hierogyyphs enabled a Frenchman called Champollion to work out the meaning of the hieroglyphs. The modern science of Egyptology began in 1824 when he published his findings.
In 1827 a British Egyptologist started the first serious study of the tombs in the Valley of The Kings. He began by painting a big number in blue paint on the entrance to all the tombs he could find. These numbers are still visible today, with KV (for Kings’ Valley) 1 at the entrance to the Valley and KV 21 near the end. This numbering system is still being used today, except that tombs after KV 21 are numbered in the order in which they have been discovered rather than in their position in the Valley. Tutankhamen’s tomb is KV 62 but it is next to KV 9.
Sometimes it is possible to find out who the tomb was built for by the hieroglyphs on the wall paintings in it (tomb robbers would not usually have damaged these), but there are a few “mystery” tombs. Two of these are KV 55 and KV 21.
KV 55 contains a single mummy and a coffin. The coffin had belonged to a King or Great Royal Wife but all the hieroglyphs containing the name had been hacked away. The mummy is not in very good condition and when it was first discovered it was not certain whether it was a man or a woman. KV21 contains two mummies, in very good condition, but no coffins. They are both very beautiful women, and are known as The Older Woman and the Younger Woman.
All three bodies were mummified in a way which dates them to about the time of Akhenaten. But until very recently no one was certain who they were. Lots of people have had ideas of course: more has been written about KV 55 and KV 21 than all other tombs put together.
Very recently the three mummies, and also Tutankhamen himself, have been the subject of a lot of new forensic tests, including CT scans (a special type of scan, usually used on living people, which builds up a three-dimensional image of the inside of a human body). These tests have shown that the hair of the Older Woman matches the lock of Tiy’s hair in Tutankhamen's tomb, that the Younger Woman is probably Tutankhamen’s mother and that the mummy in KV 55 is probably Tutankhamen’s father. This makes the three mummies Akenaten, Tiy and Kiya.
Ankhesetamun outlived Tutankhamen, and probably both Ay and Horemheb as well, and may have remarried, but we do not know where she is buried. Today there are no more “mysterious” tombs containing a mummy which could be Nefertiti, so Egyptologists are still looking for her.
