You have the stage, down stage by the audience, Stage right the stage to the audience's right, Stage left the stage to the audiences left, up stage the back of the stage, the wings, the area that is to stage right or left where the actors enter the stage or exit the stage. The green room, where the actors meet the audience prior to or after the show. Orchestra pit, usually down stage between the audience and the stage. The fly traps, the walkways above the stage where lights and special effects may be lowered to the stage. Lighting booth usually in the back of the theater where the light and sound equipment is operated. Dressing room where the actors change.
Stage left and stage right are defined in relation to the actor's position when they are facing the audience. Therefore, stage left is actually to the audience's right as they look at the stage. Stage right is to the audience's left.
Well obviously there are the actors and musicians (if it is a musical). Then there is the technical side which includes set, props, costumes, hair, makeup, lights, sound, etc. Then there are the directors and stage managers!