Many religious scholars agree that Nimrod didn't die a natural death. Jewish tradition says that Nimrod died after a gnat entered his brain and gnawed on it. Some Jewish historians claim that Nimrod suffered from the pain for forty years before he died. Islamic tradition largely supports this interpretation but replaces the gnat with a mosquito.
In the Bible (Genesis 10), Nimrod is described as a mighty hunter. He possessed extraordinary strength and ruled over the kingdoms of Babel, Erek, Akkad, and Kalneh in the land of Shinar. However, there's no discussion of how Nimrod met his end.
Both the Bible and first-century historian Flavius Josephus agree that Nimrod was a rebel leader. Josephus maintained that it was Nimrod who set up the world's first totalitarian government.
Meanwhile, the extra-biblical text of Jasher says that Esau beheaded Nimrod with his sword. Other religious scholars argue that Nimrod was actually murdered by his great-uncle, Shem.
According to this theory, Shem had Nimrod's body cut into pieces and sent out to the nations as a warning against idolatry. Religious scholar Alexander Hislop says that Nimrod was actually Ninus, a Babylonian king.
Hislop wasn't the first to make the claim. Many historians from antiquity and the Middle Ages believed that Nimrod was Ninus and the founder of idol worship. Near the end of the first century, Clement, in his Clementine Recognitions, alleged that the Greeks knew Nimrod as Ninus.
This Ninus, according to Clement, introduced all magic arts to mankind.
As can be seen, there's no consensus on how Nimrod died. That said, religious scholars and historians concede that Nimrod didn't die a natural death, he rebelled against God and taught others to do the same, and he possessed extraordinary height and strength.