Fixed-role therapy refers to Kelly's brand of therapy whereby he would assign a role for his clients to play that was distinctly different from the client's self-characterization. With this type of therapy, the therapist acts much like a supporting actor. Please see also Self-characterization.
Other definition:
Fixed role therapy is defined as a Psychotherapeutic technique in which the client acts out constructs appropriate for a fictitious person. This shows the client how the new constructs can be more effective than the old ones he/she has been using.