Birth name: Tuthmosis ("Born of the God Thoth")
Throne name: Menkheperre ("Lasting is the Manifestation of Re")
Rule: 1504 - 1450 BC (5th king of the 18th dynasty, New Kingdom)
Noteworthy relatives: Tuthmosis II (father), Hatshepsut (step-mother), Amenhotep II (son), Tuthmosis I (grandfather)
Tuthmosis III was the son of Tuthmosis II and a harem girl. His father was frail and sickly and died in his early thirties, so Tuthmosis III inherited the throne as a very young child. Because he was so young, his step-mother Queen Hatshepsut acted as his regent. A regent is a person who rules for a child until the child is old enough to take over.
After about two years of "helping" him, Hatshepsut made a bold move. She declared herself pharaoh— so she was now the king, not the queen! This put Tuthmosis III out of the picture, so we don't know much about how he spent his childhood, although he did join the army as a young man.
Tuthmosis III rightfully became pharaoh after Hatshepsut died in 1483 BC. Since her mummy has never been found, no one knows how she died, but many speculate that Tuthmosis III may have had a part in her death. He hated her so much for swiping his position that he ordered her monuments destroyed, her statues smashed, and her name and image scratched out wherever it appeared. Ancient Egyptians had a strong belief in the power of images. By destroying her statues and wiping out her name, he was both erasing the memory of her life and also canceling her existence in the afterlife!
Tuthmosis III went on to become one of the greatest warrior pharaohs of Egyptian history. He reestablished an Egyptian presence in Nubia and extended Egypt's rule all the way up to the the fourth cataract of the Nile. He led his army in wars against the Phoenicians and constantly attacked the Syrians, every summer for 18 years! He was said to have conquered 350 cities in the region, including Joppa, Kadesh, and Meggido. Conquered cities had to pay tribute ("protection" money), so there was a lot of wealth coming in to Egypt, thanks to Tuthmosis III!
During the New Kingdom, royal tombs were built high in the cliffs of Upper Egypt in a spot commonly called "The Valley of the Kings." The intention was to make the tombs as inaccessible to grave robbers as possible: Tuthmosis III's tomb entrance was halfway up the face of a cliff! But it still was broken into and plundered.
Around 1000 BC, a group of priests gathered up all the royal mummies and stored them in two secret "mummy caches" (one near Deir el-Bahari, and the other in the tomb of Amenhotep II) to keep them safe. These hidden royals were nowhere to be found for almost 2,000 years: in 1881, the 40 mummies in the Deir el-Bahari location were found; then in 1898 the tomb of Amenhotep II with its additional 16 mummies was discovered. Tuthmosis III was in the 1881 cache. His body was identified by the scraps of linen bandaging that still clung to it. The mummy had been badly damaged long ago by robbers, and it was "repaired" by the ancient priests by strapping four boat oars to the mummy's sides to keep it reinforced. It was laying in one of his original coffins, although the gold gilding had been stripped by tomb robbers.
Tuthmosis III. By TuthmosisIII.JPG: en:User:Chipdawes derivative work: Oltau (TuthmosisIII.JPG) [Public domain or Public domain], via Wikimedia Commons
Mummified head of Tuthmosis III. By Grafton Elliot Smith [Public domain], via Wikimedia Commons
Layout of KV34 (Tomb of Tuthmosis III). By R.F.Morgan (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons
Watch: "Ancient Egypt's Greatest Warrior - Tuthmosis the 3rd." National Geographic documentary