In the theater, an understudy is a person who learns the part of a leading performer. The understudy takes over the part if the main actor or actress is unable to perform due to illness, injury, or other unforeseeable circumstances. Typically, an actor or actress is an understudy for a main character while still performing a smaller role within a particular production. In other cases, however, an understudy has no assigned regular part within the performance and simply acts as a standby who can step in when needed. An understudy is sometimes called a "swing" in a musical or a "cover" in an opera.
In many ways, being an understudy is even more difficult than playing the lead role in a theatrical performance. The understudy must learn all of the lines and blocking of the lead character, yet he/she receives minimal compensation and almost no public recognition. If the understudy is called to perform on stage, he/she must be ready with just a moment’s notice. To further complicate matters, it’s not uncommon for an understudy to be expected to learn the lines for three or more parts within one performance. This helps the producers keep a show’s cost down, but it’s a stressful experience for any performer.
For an aspiring actor or actress, working as an understudy is often the first step to a long and possibly prosperous career. Understudies work closely with well-known talent, typically making valuable networking connections in the process of rehearsing and learning a role. An understudy also receives great exposure if he/she is actually allowed to fill in during a performance. In fact, Anthony Hopkins got his first big break filling in for the role of Edgar during August Strindberg’s The Dance of Death when Laurence Olivier came down with appendicitis in the middle of the production run.
While understudies do serve a very useful purpose, it is interesting to note that they are not always part of a performance. The Actors' Equity Association, a labor union representing many actors and stage managers in the United States, does not contractually obligate many shows to hire understudies. Since there is no guarantee an understudy will even be necessary, some producers of smaller shows opt to simply go without understudies in an effort to save money on production costs. In the event a crucial actor or actress is unable to play a part, the show is simply canceled or rescheduled for a later date.