Flagstar at Westbury Music Fair is known initially as the Westbury Music Fair. It is an entertainment venue located at 960 Brush Hollow Road, Westbury, New York, United States. The theater was opened for the public on June 18, 1956. It has a seating capacity of around 2,870 people at a time. The renovation of the theatre took place in the year 1965 and 1992. The venue is owned and operated by Live Nation Entertainment.

The venue has a long naming list of the stars and groups who have performed here at the Westbury Theatre. Some of the major names are Bob Weir, Alan Jones, Jack Benny, Chicago, The Pointer Sisters, Liza Minnelli, Stevie Wonder, RatDog, Tony Bennett, The Supremes, Frankie Vallie, Eric Burdon and The Animals, John Serry Sr, Don Rickles, Johnny Carson, Roger Whittaker, Bobby Sherman, Sergio Franchi, The Carpenters, and many other famous artists have come at the theatre and entertained the crowd with their energetic performances. The arena is the regular venue for the nonstop wrestling action being round in construction. Hence, it is considered being a suitable arena for professional wrestling events.