In geometry, a complex Lie group is a Lie group over the complex numbers; i.e., it is a complex-analytic manifold that is also a group in such a way G × G → G , ( x , y ) ↦ x y − 1 {\displaystyle G\times G\to G,(x,y)\mapsto xy^{-1}} is holomorphic. Basic examples are GL n ( C ) {\displaystyle \operatorname {GL} _{n}(\mathbb {C} )} , the general linear groups over the complex numbers. A connected compact complex Lie group is precisely a complex torus (not to be confused with the complex Lie group C ∗ {\displaystyle \mathbb {C} ^{*}} ). Any finite group may be given the structure of a complex Lie group. A complex semisimple Lie group is a linear algebraic group.
The Lie algebra of a complex Lie group is a complex Lie algebra.