Yin or YIN may refer to:

• the dark force in the yin and yang from traditional Chinese philosophy and medicine
• Yīn (surname) (殷), a Chinese surname
• Yīn (surname 陰), a Chinese surname 
• Yǐn (surname) (尹), a Chinese surname
• Yìn (surname) (印), a Chinese surname
• Shang dynasty, also known as the Yin dynasty
  • Yinxu or Yin, the Shang dynasty capital now in ruins
• Yin (Five Dynasties period), a short-lived kingdom during China's Five Dynasties and Ten Kingdoms period
• Yin Mountains, a mountain range in Inner Mongolia and Hebei province in China
• Yin (尹, yǐn), an office of early China sometimes equivalent to prime minister and sometimes to governor
  • Prime minister (Chu State), known in Chinese as Lingyin.
• YIN, the IATA code for Yining Airport, Xinjiang, China