Including BBOTT and the Celebrity Big Brothers. The HouseGuests that make up the top 50% of confessionals get declared to be the "main cast." For example if Glenn gets 25%, and the next most is Steve with 15%, and the next most is Cliff with 10%, then those 3 would be the "main cast."
BBOTT
Jason Roy
Morgan Willett
Danielle Lickey
Shelby Stockton
CBB1
Ross Mathews
Omarosa Manigault
James Maslow
Shannon Elizabeth
CBB2
Tamar Braxton
Tom Green
Lolo Jones
Kandi Burruss