- de Xaxàs, Alberto Dou Mas (?, ?–?)
- Xenagoras (Ancient Greece, ?–?)
- Xenocrates (Ancient Greece, 390s BC–310s BC)
- Xia, Daoxing (China, born 1930)
- Xia, Zhihong (China, born 1962)
- Xian, Jia (Medieval China, ?–?)
- Xianghao, Wang (China, 1915–1993)
- Xiaotong, Wang (Medieval China, ?–640)
- Xiaoyun, Wang (?, born 1966)
- Ximenes, Leonardo (Italy, 1716–1786)
- Xin, Zhouping (China, ?–?)
- Xing, Yi (Medieval China, 683–727)
- Xiping, Zhu (China, born 1962)
- Xu, Chenyang (China, ?–?)
- Xu, Jinchao (USA/China, born 1961)
- Xuhua, He (?, born 1979)