Gao Huan (simplified Chinese: 高欢; traditional Chinese: 高歡; pinyin: Gāo Huān) (496 – 13 February 547), Xianbei nickname Heliuhun (賀六渾), formally Prince Xianwu of Qi (齊獻武王), later further formally honored by Northern Qi initially as Emperor Xianwu (獻武皇帝), then as Emperor Shenwu (神武皇帝) with the temple name Gaozu (高祖), was the paramount general and a minister of the Xianbei-led Northern Wei dynasty and its branch successor state Eastern Wei dynasty. Although he was an ethnic Han, Gao was deeply influenced by Xianbei culture and was often considered more Xianbei than Han by his contemporaries. During his career, he and his family became firmly in control of the Eastern Wei court. Eventually, in 550, his son Gao Yang forced Emperor Xiaojing of Eastern Wei to yield the throne to him, establishing the Gao clan as the imperial house of a new Northern Qi dynasty.

Gao Huan was born in 496, at Northern Wei's northern garrison town Huaishuo (懷朔鎮, near Guyang in modern Baotou, Inner Mongolia). He was ethnically Han, but his family, having resided at Huaishuo ever since his grandfather Gao Mi (高謐) was exiled there for faults while serving as a Northern Wei official, had largely been acculturated in the Xianbei ways. His father was Gao Shusheng (高樹生), and his mother was Han Qiji (韩期姬), and Gao Shusheng's wife. His parents died soon after his birth, and he was raised at the house of his older sister Gao Loujin (高娄斤) with her husband, Wei Jing (尉景). In his young days, his family was poor, and he became a servant at the old Northern Wei capital Pingcheng (平城, in modern Datong, Shanxi). While serving at Pingcheng, Lou Zhaojun, an ethnic Xianbei and the daughter of a wealthy house, saw him and was impressed with his appearance and behavior, and she married him despite her parents' opposition. It was only after this marriage that Gao had sufficient money to buy a horse, and he became a courier for the Pingcheng defense headquarters, often delivering official mail to and from the capital Luoyang.

In 519, Gao happened to be at Luoyang when a mob of soldiers, angry over the minister Zhang Yi (張彝)'s new policy of excluding soldiers from civil service, sieged Zhang's house and then killed him. The regent Empress Dowager Hu (Emperor Xiaoming's mother) did not dare to punish them, but largely pardoned them except for eight leaders. Gao was unimpressed by Empress Dowager Hu's actions and believed that Northern Wei was on the verge of collapse. When he returned to Pingcheng, he sold his properties and used the funds to gather associates around him, stating that if disturbances occurred, the property might not be his any more anyway. His associates around this time included people from diverse ethnic backgrounds such as Xianbei, Chinese and Xiongnu, in addition to his brother-in-law Wei Jing, Sima Ziru (司馬子如), Liu Gui (劉貴), Jia Xianzhi (賈顯智), Sun Teng (孫騰), Hou Jing (侯景), and Cai Jun (蔡儁). Together they were often in the countryside, and when they saw injustices, they would seek to correct them.

In 525, in the midst of the Rebellion of the Six Frontier Towns (Chinese: 六镇之乱) against Northern Wei's rule, Gao and his associates joined one of the major Xianbei and Turkic rebel leaders, Du Luozhou (杜洛周). However, Gao soon became unimpressed with Du's behavior, and he escaped from Du's army. He then joined another rebel leader, Ge Rong, but eventually went to the Northern Wei general and Xiongnu tribal leader Erzhu Rong. By this time, Liu Gui, a Xiongnu descendant and close friend of Gao Huan was already serving under Erzhu, and he often praised Gao's talent, but when Erzhu met Gao, he was not initially impressed as Gao was poor, and looked haggard and unconfident. However, when Gao was able to tame a very wild horse, Erzhu became impressed, and they became closer and closer, with Gao pointing out that with the empire in disarray, it would be a good opportunity for Erzhu to seize power.

Gao Huan was descended from a Han Chinese family, at least paternally. However, at the same time he maintained a very public culturally Xianbei appearance. He claimed the Bohai Chinese Gao clan (渤海高氏) as his ancestors and Bohai his ancestral land, but had become de-Sinicized. It was recorded that he would make speech to his soldiers only in the Xianbei language instead of Chinese, unless one of his most fiercest generals - Gao Aocao was at the scene, he would then switch his use of language from Xianbei to Chinese, Gao Aocao was one of the few ethnic Chinese whom had earned respect from Gao Huan. Gao Huan was also reported as having frequently said to his soldiers in Xianbei language that the native Chinese "are your slaves," "they bring you supplies and clothing", while simultaneously telling the native Chinese that the Xianbei "are your clients" and "they fight for you and enable you to have peace and order". He had become Xianbeified as his clan had lived in Xianbei cultural region for some time after being relocated from what is now modern Hebei (Bohai). The Eastern Wei enfeoffed the land of Bohai to Gao Huan, and he became "Prince of Bohai" or "King of Bohai". Before Gao's death, he sang the "Song of the Chile" (敕勒歌; considered by many scholars as a military song for all Xianbeified soldiers) together with his trusted Chile general Hulü Jin in front of most of his major Xianbei, as well as Xianbeified Xiongnu, Chile and Chinese generals, and wept bitterly. He also pointed out that his powerful Chinese general Hou Jing was capricious, cunning and could not be trusted, who will rebel after his death, he then appointed several Xianbei and Chile generals whom he considered to be both upright and talented to be on guard of Hou Jing. In the end Hou did rebel against Gao Huan's son Gao Cheng, but the rebellion was successfully put down by Eastern Wei's senior general Murong Shaozong.

Erzhu Rong was impressed with Gao Huan's talents, and he made Gao one of his military commanders. In 528, Emperor Xiaoming, displeased at the hold on power that Empress Dowager Hu's lover Zheng Yan (鄭儼) and Zheng's associate Xu Ge (徐紇) had, entered into a conspiracy with Erzhu to have Erzhu advance on the capital to force Empress Dowager Hu to kill Zheng and Xu. Erzhu therefore began to march on the capital, and he made Gao his forward commander. On the way, however, Emperor Xiaoming ordered him to stop, but the news of the conspiracy still leaked, and Empress Dowager Hu poisoned Emperor Xiaoming to death and declared his distant toddler nephew Yuan Zhao emperor.

Erzhu refused to recognize Yuan Zhao as emperor, and he continued his march on Luoyang, declaring Yuan Ziyou the Prince of Changle emperor (as Emperor Xiaozhuang). Luoyang's defenses collapsed, and Erzhu arrested and threw Empress Dowager Hu and Yuan Zhao into the Yellow River to drown. Believing that the imperial officials would never obey him, he massacred a large number of them (including Emperor Xiaozhuang's brothers), and Emperor Xiaozhuang, fearing what would come next, offered to yield the throne to Erzhu. Gao suggested that Erzhu accept the offer, but Erzhu hesitated and ultimately ruled against it. His general Heba Yue, who opposed Erzhu's taking of the throne, suggested Erzhu that Gao should be executed to show his good faith, but Erzhu ruled against it. In fact, for Gao's contributions to the campaign, Emperor Xiaozhuang created him the Count of Tongdi.

Erzhu subsequently carried out a number of campaigns against agrarian rebels to try to reunify the empire. Gao thereafter participated in the campaigns against Ge Rong and Xing Gao, as well as the rebel general Yang Kan, serving with distinction. On one occasion, when Erzhu Rong was asking his commanders for opinions on who could succeed him as the commanding general of the army if he were no longer there, most opined that Erzhu Zhao could, but Erzhu Rong himself opined that Gao Huan was the only one capable of doing so, and he warned Erzhu Zhao, "You are no match for Gao Huan, and one day he will surely pierce through your nose." Erzhu Rong thereafter made Gao the governor of Jin Province (晉州, roughly modern Linfen, Shanxi), and while governor, Gao gathered much wealth, intending for use later.