Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each other * Complex (psychology), a core pattern of emotions etc. in the personal unconscious organized around a common theme such as power or status Complex may also refer to:

Arts, entertainment and media

* Complex (English band), formed in 1968, and their 1971 album ''Complex'' * Complex (band), a Japanese rock band * Complex (album), ''Complex'' (album), by Montaigne, 2019, and its title track * Complex (EP), ''Complex'' (EP), by Rifle Sport, 1985 * Complex (song), "Complex" (song), by Gary Numan, 1979 * Complex Networks, publisher of magazine ''Complex'', now online

Biology

* Protein–ligand complex, a complex of a protein bound with a ligand * Exosome complex, a multi-protein intracellular complex * Protein complex, a group of two or more associated polypeptide chains * Species complex, a cluster of very similar species difficult to delimit * Pre-Bötzinger complex, a cluster of interneurons in the ventral respiratory group of the medulla of the brainstem

Chemistry

* Coordination complex, a central atom or ion and a surrounding array of bound molecules or ions * Chelate complex, a coordination complex with more than one bond

Mathematics

* Complex number, an extension of real numbers obtained by adjoining imaginary numbers * Complex polytope, a generalization of a polytope in a complex Hilbert space * Complex analysis, the study of functions of complex numbers * Complex, an element of a field of sets * Chain complex, an algebraic structure * Simplicial complex, a kind of topological space ** CW complex, a kind of topological space * Line complex, a 3-dimensional family of lines in space

Geology

* Complex (geology), a unit of rocks composed of rocks of two or three types * Complex crater, a type of large impact crater morphology * Volcanic complex, a group of volcanoes * Complex volcano, a volcano of mixed form * Accretionary complex, a fossil accretionary wedge

Other uses