A theatre director or stage director is a practitioner in the theatre field who oversees and orchestrates the mounting of a theatre production (a play, an opera, a musical, or a devised piece of work) by unifying various endeavours and aspects of production. The director's function is to ensure the quality and completeness of theatre production and to lead the members of the creative team into realising their artistic vision for it. The director therefore collaborates with a team of creative individuals and other staff, coordinating research, stagecraft, costume design, props, lighting design, acting, set design, stage combat, and sound design for the production. If the production he or she is mounting is a new piece of writing or a (new) translation of a play, the director may also work with the playwright or translator. In contemporary theatre, after the playwright, the director is generally the primary visionary, making decisions on the artistic concept and interpretation of the play and its staging. Different directors occupy different places of authority and responsibility, depending on the structure and philosophy of individual theatre companies. Directors utilize a wide variety of techniques, philosophies, and levels of collaboration.

Ein Regisseur (von frz. régisseur, régir „leiten“), auch Spielleiter genannt, führt Regie und ist damit traditionell neben dem Schauspieler die entscheidende Person bei der Aufführung von Werken der darstellenden Kunst. Als Alternative zur Zentralgewalt des Regisseurs wurden verschiedene Ansätze von (mehr oder weniger) gleichberechtigten Regieteams entwickelt.

Regissör är den person som utövar regi. Ordet regi kommer av latinets rego som betyder ungefär styra, leda. En filmregissör leder arbetet vid en filminspelning. Teaterregissörer leder arbetet vid teateruppsättningar.

Reżyser - osoba realizująca własną artystyczną koncepcję sztuki teatralnej, filmu, audycji radiowej, programu telewizyjnego itp. Koordynuje działania wszystkich członków ekipy danego przedsięwzięcia i odpowiada za jego ostateczny kształt. Reżyser musi dbać o właściwe wyeksponowanie myśli autora sztuki bądź scenarzysty.

O encenador, director teatral ou diretor de teatro é o responsável por supervisionar e dirigir a montagem de uma peça de teatro, trabalhando directamente a representação, decidindo a melhor forma de conjugar os diversos esforços da equipa de trabalho em todos os aspectos da produção. A sua função é assegurar a qualidade e integridade do produto teatral (a peça). Contactando os membros chave da equipa de trabalho, coordena o andamento das pesquisas necessárias, a cenografia, o guarda-roupa, os adereços, desenho de luzes, sonoplastia, etc.