Xu Xiake (Chinese: 徐霞客; pinyin: Xú Xiákè; Wade–Giles: Hsü Hsia-k'o, January 5, 1587 – March 8, 1641), born Xu Hongzu (徐弘祖), courtesy name Zhenzhi (振之), was a Chinese explorer, geographer, and travel writer of the Ming dynasty, known best for his famous geographical treatise, and noted for his bravery and humility.

Xiake was an alternate sobriquet (別號) given to him by his friend Chen Jiru (陳繼儒, 1558–1639) and it means "one who is in the sunset clouds".

His other friend, Huang Daozhou (黃道周, 1585–1646), also gave Xu an alternate sobriquet: Xiayi (霞逸), meaning "untrammelled in the sunset clouds."

[1] From the snowy passes of Sichuan, to the subtropical jungles of Guangxi and Yunnan, to the mountains of Tibet, Xu Xiake wrote of all his experiences and provided enormous amounts of written detail from his observations.

[4] Xu made the important realization that the Jinsha river network – and not the Min or Yalong – formed the true headwaters of the Yangtze River, correcting a mistake in Chinese geography as old as the "Tribute of Yu" compiled by Confucius in the Classic of History.