the place in a theatre, cinema etc where tickets are sold [↪ ticket office]
at the box office
Collect your tickets at the box office.
used to describe how successful a film, play, or actor is, by the number of people who pay to see them
a (big) box office draw (=a successful actor who many people will pay to see)
box office receipts/takings etc (=the number of tickets sold or the money received)