backup dancer

US /ˈbæk.ʌp ˌdæn.sər/
UK /ˈbæk.ʌp ˌdæn.sər/
"backup dancer" picture
1.

a dancer who performs with a lead singer or group, often in the background, to enhance a live performance or music video

:
She started her career as a backup dancer for a famous pop star.
The concert featured elaborate choreography with many backup dancers.