Esarhaddon, also spelled Essarhaddon, Assarhaddon and Ashurhaddon (Neo-Assyrian Akkadian: 𒀭𒊹𒉽𒀸, also 𒀭𒊹𒉽𒋧𒈾 Aššur-aḫa-iddina, meaning "Ashur has given me a brother"; Biblical Hebrew: אֵסַר־חַדֹּן‎ ʾĒsar-Ḥaddōn) was the king of the Neo-Assyrian Empire from 681 to 669 BC. The third king of the Sargonid dynasty, Esarhaddon is most famous for his conquest of Egypt in 671 BC, which made his empire the largest the world had ever seen, and for his reconstruction of Babylon, which had been destroyed by his father.

After Sennacherib's eldest son and heir Aššur-nādin-šumi had been captured and presumably executed in 694, the new heir had originally been the second eldest son, Arda-Mulissu, but in 684, Esarhaddon, a younger son, was appointed instead. Angered by this decision, Arda-Mulissu and another brother, Nabû-šarru-uṣur, murdered their father in 681 and planned to seize the Neo-Assyrian throne. The murder, and Arda-Mulissu's aspirations of becoming king himself, made Esarhaddon's rise to the throne difficult and he first had to defeat his brothers in a six-week long civil war.

His brothers' attempted coup had been unexpected and troublesome for Esarhaddon and he would be plagued by paranoia and mistrust for his officials, governors and male family members until the end of his reign. As a result of this paranoia, most of the palaces used by Esarhaddon were high-security fortifications located outside of the major population centers of the cities. Also perhaps resulting from his mistrust for his male relatives, Esarhaddon's female relatives, such as his mother Naqiʾa and his daughter Šērūʾa-ēṭirat, were allowed to wield considerably more influence and political power during his reign than women had been allowed in any previous period of Assyrian history, with the possible exception of Sammuramat in the 9th century BC.

Despite a relatively short and difficult reign, and being plagued by paranoia, depression and constant illness, Esarhaddon remains recognized as one of the greatest and most successful Assyrian kings. He quickly defeated his brothers in 681, completed ambitious and large-scale building projects in both Assyria and Babylonia, successfully campaigned in Media, Persia, Elam, the Arabian Peninsula, Anatolia, the Caucasus, and the Levant, defeated the Kushite Empire and conquered Egypt and Libya, enforced a vassal treaty upon the Medes and Persians and ensured a peaceful transition of power to his two sons and heirs Ashurbanipal as ruler of the empire and Šamaš-šuma-ukin as king of Babylonia after his death.

Sennacherib's first choice as successor had been his eldest son, Aššur-nādin-šumi, who he had appointed as the ruler of Babylon in about 700 BC. Shortly thereafter, Sennacherib attacked the land of Elam (modern day southern Iran) in order to defeat the Elamites and some Chaldean rebels which had fled there. In response to this attack, the Elamites invaded Babylonia from another route in the south of Sennacherib's empire and in 694 successfully captured Ashur-nadin-shumi at the city of Sippar. The prince was taken back to Elam and probably executed, causing Sennacherib to wreak savage revenge on the Elamites, Chaldeans, and Babylonians.

After Aššur-nādin-šumi's presumed death, Sennacherib elevated his second eldest surviving son, Arda-Mulissu, as crown prince. After several years as crown prince, Arda-Mulissu was replaced as heir by Esarhaddon in 684. The reason for Arda-Mulissu's sudden dismissal from the prominent position is unknown, but it is clear that he was very disappointed. Esarhaddon described the reaction of his brothers to his appointment as heir in a later inscription:

Of my older brothers, the younger brother was I. But by decree of [the gods] Ashur and Shamash, Bel and Nabu, my father exalted me, amid a gathering of my brothers he asked Shamash, "is this my heir?" and the gods answered, "he is your second self".
And then my brothers went mad. They drew their swords, godlessly, in the middle of Nineveh. But Ashur, Shamash, Bel, Nabu, Ishtar, all the gods looked with wrath on the deeds of these scoundrels, brought their strength to weakness and humbled them beneath me.

Arda-Mulissu was forced to swear loyalty to Esarhaddon by his father, but repeatedly appealed to Sennacherib to again accept him as heir instead. These appeals were not successful, and Sennacherib came to realize that the situation was tense, so he sent Esarhaddon into exile in the western provinces for his own protection. Esarhaddon was unhappy with his exile and blamed his brothers for it, describing it with the following words: