Big Brother 27,' hosted by Julie Chen Moonves, premieres on Thursday,. See which houseguests are in power as HoH, who is nominated and who has been evicted so far

Big Brother follows a group of people living together in a house outfitted with more than 100 cameras and 100 microphones, recording their every move 24 hours a day. Each week, someone will be voted out of the house, with the last remaining Houseguest receiving the grand prize of $750,000.

After much anticipation, Big Brother Season 27 revealed the mystery houseguest. Former contestant and winner of the thirteenth season, Rachel Reilly, joined the CBS show as the mystery houseguest.

It's also worth noting that when CinemaBlend spoke to Rachel back in 2021, she was eager to play Big Brother again. Fans may remember she wanted to be a part of Season 22's second All-Stars season, but was not able to play because she was pregnant at the time. Now, it would appear she's playing the game again, but for how long is anyone's guess.

"So there's going to be a strong reaction in both directions for this mystery Houseguest."Ahead of season 27, here are the 12 best Big Brother seasons to watch, all of which are available to stream on Paramount+.

Everything you need to know about ‘Big Brother’ season 27, including how to watch, where to stream the live feeds, and the cast.

Sleeper car bunk room: Behind a secret entrance, this train-themed bedroom straight out of a murder mystery novel contains bunkbeds for six Houseguests (the first time the BB house has had bunk beds since season one!) and a sleek Art Deco design.