drop curtain
US /drɑːp ˈkɜːr.tən/
UK /drɑːp ˈkɜːr.tən/

1.
a curtain that is lowered onto a stage to separate it from the audience or to mark the end of a performance
:
•
The drop curtain fell, signaling the end of the play.
•
The stagehands prepared the drop curtain for the next act.