One of the most controversial rulers in ancient Egyptian history, Akhenaten (formerly Amenhotep IV) was never meant to be king. The second son of pharaoh Amenhotep III (and grandson of Thutmose IV), he was preceded in the line of succession by his elder brother Prince Thutmose. After Thutmose's untimely demise, however, Prince Amenhotep found himself in the royal spotlight, and following Amenhotep III's death in 1353 B.C.E., he was crowned pharaoh. Over the course of his 17-year-reign, the king would usher in a new era in Egyptian history, a time of religious and cultural reform that some called revolutionary, and some, heresy.
With his Great Wife Nefertiti by his side, Amenhotep IV began his rule in a fairly conventional manner. He added to the Karnak temple complex, paid homage to Amun, and even held his own Sed festival in Regnal Year 3. Despite his attempts to keep up appearances, Amenhotep's true agenda soon became apparent. The pharaoh began construction on a giant new temple complex in the same area as Karnak (Gempaaten), dedicated not to Amun but to another "fringe" deity: the Aten. The Aten was not your average Egyptian sun god (like Ra, Amun-Ra or Re-Horakhty, etc), a humanoid or anthropomorphic representation of some aspect of the sun's power. The Aten was the literal, physical representation of the sun disk itself: it was pure, natural power, with no human characteristics. Because of this, Amenhotep IV could tie himself to the Aten, making himself not only a deified pharaoh, but the human manifestation of the Aten on earth. In Regnal Year 5, the king changed his name from Amenhotep ("Amun is Satisfied") to Akhenaten ("Effective for the Aten"), officially making his change in religious policy. Nefertiti followed suit, adding to her royal titles "Neferneferuaten", meaning "Beauteous are the Beauties of the Aten".
After this point, the Aten became the official state god of Egypt. Akhenaten rejected the cult of Amun and the worship of Egypt's pantheon of other deities: there was only the sun disk. The cult of the Aten during Akhenaten's reign is widely considered to be one of the first instances of monotheism in history. In another display of his devotion to the Aten, the pharaoh decided to build Egypt a new capital city, completely dedicated to god. Located in the desert halfway between Thebes and Memphis, Akhenaten named his city "Akhetaten," "The Horizon of the Aten," bust most egyptologists today refer to it by its modern name, Amarna.
Akhenaten's reign, the fittingly-named "Amarna Period," is notable not only for its radical religious changes, but for its distinctive artistic and architectural style as well. For instance, temples to the Aten were vastly different in layout and construction than temples to Amun or another god. In place of a dark, closed-in private sanctuary to house the statue of the deity, temples to the Aten were open-air structures, allowing the complex direct access to the sun disk's light. Within these complexes, like the Gempaaten temple outside of Karnak, were some very intriguing images of Akhenaten and the royal family worshipping the sun disk. Instead of following the conventions of traditional Egyptian artwork, the murals and statuary of the Amarna Period were created in an odd, distorted style. All depictions of Akhenaten give the king very distinctive features: a long face with large lips and slit eyes, spindly limbs, and a feminine body shape. Queen Nefertiti and the couple's six daughters were also portrayed in this distorted fashion (often in strikingly casual and touching scenes from their daily life). Why was this so? After generations of inbreeding and brother-sister marriages, it's quite possible that this is what Akhenaten actually looked like. However, the pharaoh's unusual appearance could also be the result of a religious/symbolic statement. Just like the Aten was genderless, so was its vessel on earth, and it was therefore only fitting for Akhenaten to exhibit both masculine and feminine traits.
Following Akhenaten's death in 1336 B.C.E., the Egyptian people were quick to dismantle the new religious order their king had imposed. Viewed by most as a heretic, the Aten cult was quickly abandoned and worship of Amun and the other gods soon resumed. The Egyptian capital was moved back to Thebes, the city of Amarna completely abandoned. Images of the king and his family were destroyed, and his name omitted from the official king lists. Akhenaten's immediate successor was a short-lived pharaoh named Smenkhare (believed by many to have been Nefertiti ruling as a female pharaoh) however, the mantle of kingship soon passed to the heretic's young son and only heir, Tutankhamun.