Theatre practitioner is a modern term to describe someone who both creates theatrical performances and who produces a theoretical discourse that informs his or her practical work. A theatre practitioner may be a director, a dramatist, an actor, or—characteristically—often a combination of these traditionally-separate roles. "Theatre practice" describes the collective work that various theatre practitioners do.
You can also describe it as engaged into arts and theatre or drama
The term is not ordinarily applied to theatre-makers prior to the rise of modernism in the theatre, instead describing theatre praxis from Stanislavski's development of his 'system', through Meyerhold's biomechanics, Antonin Artaud's Theatre of cruelty, Bertolt Brecht's epic and Jerzy Grotowski's poor theatre, down to the present day, with contemporary theatre practitioners including Augusto Boal with his Theatre of the Oppressed, Dario Fo's popular theatre, Eugenio Barba's theatre anthropology and Anne Bogart's viewpoints.