Supernumerary (noun)

1. A person who is employed in addition to the regular staff, typically to do nonessential or extra work.
2. A person who is present but not taking an active part in a situation or event.

Origin:

Late 17th century, from latin supernumerarius, from super- + numerarius "related to numbers".

Examples:

1. The theater company had a number of supernumeraries on hand to fill in as extras in the crowd scenes.
2. As a supernumerary employee, he was often asked to do tasks that were not part of his usual job responsibilities.
3. The supernumeraries at the wedding were seated in a separate section of the church during the ceremony.
4. Supernumeraries were used in the theater production to fill out the crowd scenes and help create a sense of realism.
5. The supernumerary was happy to do whatever was needed to help the production run smoothly.