True Martial Great Emperor(真武大帝):
In Chinese, it is pronounced as: zhēn wǔ dà dì，Written as:

The True Martial Great Emperor, also known as the Mysterious Heavenly Supreme Deity, the Protector True Sovereign, and the Black Tortoise Great Emperor, among other titles such as the Demon-Quelling Celestial Venerable, the Gratitude-Repaying Ancestral Master, and the Unkempt-Hair Ancestral Master, is a famously revered deity in Taoism. Hubei’s Wudang Mountain serves as the Ashram of the True Martial Great Emperor.
Originally, the True Martial Great Emperor was the ancient Divine Beast, the Black Tortoise, one of the four great Divine Beasts in our country’s ancient mythology, which also includes the Azure Dragon, the White Tiger, and the Vermilion Bird, each representing the four cardinal directions of East, West, South, and North, respectively. Unlike the other three, the Black Tortoise is a spirit formed by the combination of a turtle and a snake, while the others are individual spirits.
In ancient times, the worship of animal totems was common, with the turtle revered for its longevity and as a symbol of immortality, and the snake, due to its resemblance to the dragon, was combined with the turtle. This fusion created the revered image of the Black Tortoise.
Due to strong royal support, the status of the True Martial Great Emperor reached its zenith during the Ming Dynasty, with temples dedicated to him spread across the realm, and he was formally recognized as a major deity in Taoism.