A xian is any manner of immortal, mythical being within the Taoist pantheon or Chinese folklore. Xian has often been translated into English as "immortal".

Taoism or Daoism is a diverse tradition indigenous to China, variously characterized as both a philosophy and a religion. Taoism emphasizes living in harmony with the Tao—generally understood as being the impersonal, enigmatic process of transformation ultimately underlying reality. The concept originates in the Chinese word 道, which has numerous related meanings: possible English translations include 'way', 'road', and 'technique'. Taoist thought has informed the development of various practices within the Taoist tradition and beyond, including forms of meditation, astrology, qigong, feng shui, and internal alchemy. A common goal of Taoist practice is self-cultivation resulting in a deeper appreciation of the Tao, and thus a more harmonious existence. There are different formulations of Taoist ethics, but there is generally emphasis on virtues such as effortless action, naturalness or spontaneity, simplicity, and the three treasures of compassion, frugality, and humility. Many Taoist terms lack simple definitions and have been translated in several different ways.