The Yongle Emperor (pronounced [jʊ̀ŋ.lɤ̂], yong-luh; 2 May 1360 – 12 August 1424) — personal name Zhu Di (WG: Chu Ti) — was the third Emperor of the Ming dynasty, reigning from 1402 to 1424.

Zhu Di was the fourth son of the Hongwu Emperor, the founder of the Ming dynasty. He was originally enfeoffed as the Prince of Yan (燕王) in May 1370, with the capital of his princedom at Beiping (modern Beijing). Amid the continuing struggle against the Mongols of the Northern Yuan dynasty, Zhu Di consolidated his own power and eliminated rivals such as the general Lan Yu. He initially accepted his father's appointment of his eldest brother Zhu Biao and then his nephew Zhu Yunwen as crown prince, but when Zhu Yunwen ascended the throne as the Jianwen Emperor and began executing and demoting his powerful uncles, Zhu Di found pretext for rising in rebellion against his nephew. Assisted in large part by eunuchs mistreated by the Hongwu and Jianwen Emperors, who both favored the Confucian scholar-bureaucrats, Zhu Di survived the initial attacks on his princedom and drove south to launch the Jingnan Campaign against the Jianwen Emperor in Nanjing. In 1402, he successfully overthrew his nephew and occupied the imperial capital, Nanjing, after which he was proclaimed Emperor and adopted the era name Yongle, which means "perpetual happiness".

Eager to establish his own legitimacy, Zhu Di voided the Jianwen Emperor's reign and established a wide-ranging effort to destroy or falsify records concerning his childhood and rebellion. This included a massive purge of the Confucian scholars in Nanjing and grants of extraordinary extralegal authority to the eunuch secret police. One favorite was Zheng He, who employed his authority to launch major voyages of exploration into the South Pacific and Indian Oceans. The difficulties in Nanjing also led the Yongle Emperor to re-establish Beiping (present-day Beijing) as the new imperial capital. He repaired and reopened the Grand Canal and, between 1406 and 1420, directed the construction of the Forbidden City. He was also responsible for the Porcelain Tower of Nanjing, considered one of the wonders of the world before its destruction by the Taiping rebels in 1856. As part of his continuing attempt to control the Confucian scholar-bureaucrats, the Yongle Emperor also greatly expanded the imperial examination system in place of his father's use of personal recommendation and appointment. These scholars completed the monumental Yongle Encyclopedia during his reign.

The Yongle Emperor died while personally leading a military campaign against the Mongols. He was buried in the Changling Tomb, the central and largest mausoleum of the Ming tombs located north of Beijing.