The self-proclaimed "Great Sage Who Pacifies Heaven" (平天大圣 tiān píng dà shèng), Bull-Demon King, is the main antagonist in the classic chinese novel "Journey to the West" (西游记 xī yóu jì). He is the master of Cui Yun Mountain (翠云山 cuì yún shān) and Ji Lei Mountain (积雷山 jī léi shān), his wife is the infamous Princess Iron Fan (铁扇公主 tiě shàn gōng zhǔ), and together they had a son called Red Boy (红孩儿 hóng hái ér).
The Bull-Demon King first appeared in the novel after the Monkey King (孙悟空 sūn wù kōng) obtained his Wishing Staff (如意金箍棒 rúyì jīn gū bàng) from the Dragon King, Ao Guang (敖广 áo guǎng). He is known as the Great King of the West (西方大力王 xī fāng dà lì wáng), and rides a stead called Bi Shui Jin Jing Shou (辟水金晶兽 pì shuǐ jīn jīng shòu) that can fly through the air and water.
Much like the Monkey King he knows the way of the 72 changes (七十二变 qī shí èr biàn), and has the ability to change into a giant (巨型身法 jù xíng shēn fǎ).
In the beginning, the Bull-Demon King and Monkey King became sworn brothers, alongside five other demon kings, collectively known as the Seven Great Sages (七大圣 qī dà shèng);
- Saurian Demon King (蛟魔王 jiāo mó wáng)
- Roc Demon King (鹏魔王 péng mó wáng)
- Lion Spirit King (狮狔王 shī nǐ wáng)
- Macaque Spirit King (猕猴王 mí hóu wáng)
- Snub-nosed monkey Spirit King (禺狨王 yú róng wáng)