Helü (Chinese: 闔閭) or Helu (Chinese: 闔廬) was from 514 to 496 BC king of the state of Wu toward the end of the Spring and Autumn period of ancient China. His given name was Guang (Chinese: 光); he was initially known as Prince Guang.
Prince Guang was the son of King Yumei, and the nephew of King Liao. He welcomed the Chu exile Wu Zixu into his entourage and, when he sought to usurp the throne of Wu, was introduced by him to Zhuan Zhu. Zhuan assassinated King Liao in 515 BC and the prince became King Helü. The king assigned Wu Zixu to lead the design and building of his "great city," which forms the basis of Suzhou's present old town.
In 506 BC Helü with the help of Wu Zixu and Sun Tzu, the author of The Art of War, launched major offensives against the state of Chu. They prevailed in five battles, one of which was the Battle of Boju, and conquered the capital Ying. However, Chu managed to ask the state of Qin for help, and after he was defeated by Qin, the vanguard general of Wu troops, Fugai, a younger brother of Helü, led a rebellion. After beating Fugai, Helü was forced to leave Chu. Fugai later retired to Chu and settled there.
His son, Fuchai, succeeded him in 495 BC. Helü had two other sons named Bo and Shan. Bo was initially his heir but died before him.