| Zhang Yan | |
| Full Name: | Zhang Yan |
| Father: | Zhang Ao, Prince of Zhao |
| Mother: | Princess Yuan of Lu |
| Spouse: | Emperor Hui of Han |
| Empress of the Han dynasty | |
| Succession: | Empress of the Han dynasty |
| Reign: | 192–188 BC |
| Reign-Type: | Tenure |
| Predecessor: | Empress Lü |
| Successor: | Empress Lü (Houshao) |
| Birth Date: | 202 BC? |
| Death Date: | April or May 163 BC (aged 38-39) |
| Posthumous Name: | Empress Xiaohui (孝惠皇后) |
Zhang Yan[1] (; died April or May 163 BC[2]), known formally as Empress Xiaohui (孝惠皇后) was an empress during the Han dynasty. She was a daughter of Princess Yuan of Lu (the only daughter of Emperor Gao (Liu Bang) and his wife Empress Lü) and her husband Zhang Ao (張敖, son of Zhang Er), the Prince of Zhao and later Marquess of Xuanping.
In November 192 BC,[3] at the insistence of then-Empress Dowager Lü, Lady Yan married her uncle Emperor Hui, the son of Emperor Gao and Empress Dowager Lü, and she was created empress. The marriage was a childless one. At Empress Dowager Lü's instruction, Empress Zhang took several male children as her own and killed their mothers. (Whether these children were Emperor Hui's is a matter of controversy, although it appears likely that they were Emperor Hui's children by his concubines.)
When Emperor Hui died in September 188 BC at the age of 22, one of the children that Empress Zhang adopted became emperor (as Emperor Qianshao), but Grand Empress Dowager Lü had effective total control of the imperial government. Empress Zhang, was not made empress dowager as this title was retained by Empress Dowager Lü who never claimed the title Grand Empress Dowager and did not appear to have significant influence. Nevertheless, when Emperor Qianshao found out in 184 BC that he was not actually her child, he made a careless comment that he would take vengeance on her—at which Empress Dowager Lü had him deposed and executed, and replaced him with his brother Liu Hong (as Emperor Houshao), who was also adopted by Empress Zhang. It was during Emperor Qianshao's reign that Empress Zhang's brother Zhang Yan (張偃, pinyin Zhāng Yǎn—notice difference in tone) was created the Prince of Lu.
After Empress Dowager Lü died in August 180 BC, and the Lü clan overthrown and slaughtered by the officials opposed to the Lüs in the Lü Clan Disturbance, Emperor Houshao was deposed and killed. Empress Zhang was not killed, but she was put under house arrest in a palace to the north after being deposed from her position as empress and henceforth referred to as Empress Hui. Her brother, the Prince of Lu, was also deposed and reduced in rank to Marquess of Nangong. After this no records exist of her later life until her death.[4] Empress Zhang died in 163 BC and was buried with her husband of merely four years.