A costumer or costume designer is a creative professional who specializes in developing costumes for productions on stage and screen. Costumers work with other members of the creative staff as well as actors and actresses to costume people appropriately for the production and their needs. Many costumers specialize in a particular area of interest, such as costuming for the opera or preparing costumes for television productions.
A costumer's work usually starts early in the stages of the production. The creative team, including people like the director, set designer, lighting designer, and artistic designer, meets to discuss the production. In the meeting they talk about the creative vision which accompanies the production, and the general look and feel which are desired. A period-accurate production of Hamlet for the stage, for example, has very different requirements than a television medical drama. The costumer takes notes during this meeting and starts to develop ideas.
As casting proceeds, the costumer develops costumes which are specifically designed for the bodies of their wearers, taking into account the needs of the actor or actress and the production. For instance, opera stars need to room to breathe deeply and expand their chest and diaphragms, so a highly restrictive costume is not desirable, but since opera stars also tend to be large, the customer doesn't want to drape them in amorphous garments which hide their bodies. Thus, the costumer has to strike a balance which allows the performer to sing while also maintaining the desired aesthetics.
The costumer is responsible for the overall look associated with the costumes in a production. She or he usually works with seamstresses who sew custom pieces as well as people who specialize in finding costumes for sale or rental which can be used in a production. Once a production starts, the costumer's work is taken over by the wardrobe manager, who is in charge of keeping costumes in good condition during the production. The wardrobe manager cleans, mends, makes adjustments if actors or actresses change in size and shape, and keeps track of all the costumes.
In television productions, where production is constantly beginning and ending on new episodes, the costumer may be working several episodes ahead while also keeping an eye on episodes currently on air and in production. Costumers for television often need to think about issues like hiding or accommodating pregnancies on long running shows, changing a character's look and feel over time so that the character's costumes keep progress with his or her emotional development, and even costuming different actors taking over roles with the goal of making such transitions relatively smooth.