Jili (季歷 Jìlì) was a leader of the Predynastic Zhou during the Shang dynasty of ancient China. His son King Wen and grandson King Wu would defeat the Shang to establish the Zhou dynasty. He was posthumously granted the title of king, and often referred to as Ji, King of Zhou (周王季 Zhōu-wáng Jì).

Jili was the youngest son of King Tai. Sima Qian recorded that he and his son were both renowned for their wisdom and this reputation caused his elder brothers Taibo and Zhongyong to renounce voluntarily their claims to the throne and to leave in exile to Wu.

Surviving historical records portray him travelling to the Shang capital to submit to Wu Yi and being rewarded with land, jade, and horses in 1118 BC. In 1117, he captured 20 "kings" of the Guirong tribes. During the reign of the Shang king Wen Ding, he was defeated by the Yanjing Rong but managed to subdue the Yuwu (余无), Hu (呼), and Xitu (翳徒) Rong. After the defeat of the Xitu tribe, Wen Ding became nervous and betrayed him, rewarding him richly before dispatching him to a place called Saiku (塞库), where he was killed by Shang forces.

His wife was Tai Ren (太任), who along with Jiang Yuan was credited by Sima Qian with being responsible for the rise and success of Zhou. She came from a place called Zhi (摯) and represented some connection to the Shang royalty.

Jili had at least three sons. The eldest son was King Wen whose son King Wu established the Zhou dynasty of China upon defeating the Shang at the Battle of Muye. The second eldest son was enfeoffed by King Wu in Eastern Guo, also known as (i.e. the "Second Son of Guo"), and the third eldest son in Western Guo, also known as (i.e. the "Third Son of Guo.")

周王季（？ - ？），姬姓，名歷，由於是少子，又名季歷，是周太王的第三子，周文王昌的生父。

古公亶父有三個兒子，長子太伯、次子仲雍、三子季歷。周太王認為季歷之子昌有「聖瑞」，希望昌能繼承自己的王位，光大周部落。太伯和仲雍為了讓季歷和昌能當上周部落的君主，便逃亡至荊地，斷髮、紋身，以讓季歷，隨後兩人建立吳國。

王季與殷商王室聯婚，娶摯仲氏，名任，生下周文王。據《竹書紀年》，季歷伐翳徒之戎有功，商的君主文丁忌憚，先嘉其功而監禁之，把他餓死。劉知幾記載這個說法在唐朝時有爭議。