In show business, the green room is the space in a theatre, or a similar venue, that functions as a waiting room and lounge for performers before, during, and after a performance or show when they are not engaged on stage. Green rooms typically have seating for the performers, such as upholstered chairs and sofas.

The origin of the term is often ascribed to such rooms historically being painted green. Modern green rooms need not necessarily adhere to a specifically green colour scheme, though the theatrical tradition of the name remains.