Kuchlug (also spelled Küchlüg, Küçlüg, Güčülüg, Quqluq) (Хүчлүг; ; d. 1218) was a member of the Naiman tribe who became the last emperor of the Western Liao dynasty (Qara Khitai). The Naimans were defeated by Genghis Khan and he fled westward to the Qara Khitai, where he became an advisor to his future father-in-law Yelü Zhilugu. He later rebelled, usurped the throne and took control of the empire, putting an end to the rule of the House of Yelü. He was killed in 1218 by the Mongols and the domain of the Qara Khitai was absorbed into the Mongol Empire.
While his predecessor Yelü Zhilugu was the last Qara Khitai emperor from the Yelü clan, Kuchlug is sometimes regarded as the final ruler of the Western Liao realm as he retained the dynastic title of "Great Liao" upon his ascension to the throne.
Kuchlug was the son of Taibuqa, the Tayang khan (leader) of the Naimans, a Mongol-speaking tribe. In 1204, Jamuqa, the chief Mongol rival of Temüjin (later known as Genghis Khan), fled to the Naimans. Temüjin followed and launched an assault upon the tribe, resulting in the battle of the thirteen sides. Taibuqa at first hesitated, considering it better to fall back to the Altai Mountains and attack the Mongols from there. Kuchlug, however, favored a direct assault on the Mongols on open ground. He went so far as to dismiss his father's plan as cowardly. Taibuqa relented and allowed Kuchlug to carry out his attack.
The battle was a disaster for the Naiman. Jamuqa abandoned them and fled. Taibuqa was mortally injured, and his main commander was killed. The rest of the tribe surrendered to Temüjin and were absorbed into his ranks. Kuchlug managed to escape and with a few Naiman soldiers fled westward towards the Kara Irtysh.
Afterwards Genghis Khan was wary of the threat Kuchlug still posed. In 1208, they again met in battle, and Kuchlug was pushed further west into Zhetysu. Reeling from a second defeat at the hands of the Mongols, Kuchlug turned to the Qara Khitai based in Balasagun for protection.