Zhang Yao'er (章要兒) (506–570), formally Empress Xuan (literally "the responsible empress"), was an empress of the Chinese Chen Dynasty. Her husband was the founding emperor Emperor Wu (Chen Baxian). Zhang Yao'er was from Wuxing Commandery (吳興, roughly modern Huzhou, Zhejiang). Her father Zhang Jingming (章景明) was originally surnamed Niu (鈕), but was adopted by a family named Zhang, and therefore had his name changed. Her mother was named Su (蘇), but her mother's surname is not known to history. Zhang Yao'er was not Chen Baxian's first wife, as Chen had initially married a daughter of Qian Zhongfang (錢仲方), who, like Chen and Zhang, was from Wuxing Commandery, but Lady Qian died early, so he married Zhang after Lady Qian's death. Zhang Yao'er was described as being well-versed in mathematics,