In bold, the official abbreviations
- Xantus de Vesey, J John Xantus de Vesey (1825–1894)
- Xavier Filho, L (L. Xavier) Lauro Xavier Filho
- Xavier-Leite, AB (Xavier-Leite) Amanda Barreto Xavier-Leite
- Xena, N (Xena) Nereida Xena (1955– )
- Xhonneux, G (Xhonneux) Guy Xhonneux (1953– )
- Xi, JQ (J.Q.Xi) Jing Qing Xi fl. 1987
- Xi, PG (P.G.Xi) Ping Gen Xi fl. 2000
- Xi, YW (Y.W.Xi) You Wei Xi fl. 1989
- Xia, C Canwei Xia
- Xia, NH (N.H.Xia) Nian-He Xia (1963– )
- Xian, SY Si-yuan Xian
- Xiang, CL (C.L.Xiang) Chun-Lei Xiang (fl. 2008)
- Xiang, QP (Q.P.Xiang) Qiao Ping Xiang
- Xiao, HL (H.L. Xiao) Hui-Lin Xiao
- Xiao, J Jule Xiao
- Xiao, YL (Y.L.Xiao) Yun-Li Xiao
- Xie, CH Cheng-Hui Xie
- Xie, L Lixia Xie
- Xie, LP Liping Xie
- Xie, M Meng Xie
- Xie, RD Rong-dong Xie
- Xifreda, CC (Xifreda) Cecilia Carmen Xifreda (1942– )
- Xin, DY (D.Y. Xin) De-Yu Xin
- Xing, JC Ji-Chun Xing
- Xiong, GQ Guo-Qiang Xiong
- Xiong, RC Rong-chuan Xiong
- Xiong, W (W. Xiong) Wei Xiong
- Xiong, Y Yan Xiong
- Xiong, YX (Y.X.Xiong) Yuan Xin Xiong (1954– )
- Xiong, ZP (Z.P. Xiong) Zhong-Ping Xiong
- Xu, HC (H.C. Xu) Hua-Chao Xu
- Xu, JM (J.M.Xu) Jie Mei Xu
- Xu, L (Lei Xu) Lei Xu
- Xu, LH Lihua Xu
- Xu, LW (L.W.Xu) Lian-Wang Xu
- Xu, MF Miao-Feng Xu
- Xu, N Ning Xu
- Xu, P (P. Xu) Peng Xu
- Xu, SQ (S.Q. Xu) Sheng-Quan Xu
- Xu, SY Si-Yuan Xu (Chinese Academy of Sciences)
- Xu, X Xiang Xu
- Xu, X Xing Xu
- Xu, Y Yuan Xu
- Xu, Y Yuan Xu (entomologist)
- Xu, YJ Yajun Xu
- Xu, YL (Y.L.Xu) Yao Liang Xu (1964– )
- Xu, Z Zhenghui Xu
- Xu, ZF (Z.F.Xu) Zai-Fu Xu
- Xu, ZG (Z.G. Xu) Zhen-Guo Xu
- Xu, ZK (Z.K. Xu) Zhen-Kuo Xu
- Xu, ZZ (Z.Z. Xu) Zhen-Zu Xu
- Xuarez, G (Xuarez) Gaspar Xuarez (1731–1804)
- Xue, DY (D.Y.Xue) Da-Yong Xue
- Xue, WQ (W.Q. Xue) Wan-Qi Xue
- Xue, XF (X.F.Xue) Xiao-Feng Xue
