Big Brother 9

The ninth season of Big Brother, dubbed as "The Red Button", premiered on September 29, 2015 and concluded on January 21, 2016. Kristy Craig was crowned the winner of the season by a vote of 9-0 against runner-up Chelsea Long. Craig became the first HouseGuest to be crowned the winner by a unanimous vote.

Following their appearence on this season, numerous HouseGuests have went on to appear in various other editions of the series. HouseGuest Colton Logan returned in Big Brother 10 as a candidate to return to the house by a viewer vote to enter, but did not receive enough votes to enter. Logan later returned as a HouseGuest for Big Brother 13 alongside Shane Bumgardner, where they placed 6th and 8th respectively.

Format
See Season 1 format

Some new changes are to be implemented for this season, and possibly for future seasons as well. Battle of the Block, which have been used in the sixteenth and seventeenth seasons of the American version, was confirmed to be included in this season. However, a new rule has also been implemented to address the criticisms that the twist faced, which prohibits discussion of nominations in regards to Battle of the Block.

Another twist has been hinted during the previews, which revealed that there is a "Giant Red Button" in the house that can be pressed each week. Once the button has been pressed, either a reward, punishment or twist will be given at some point during the following week without warning.

HouseGuests
Advertisements have revealed that 18 HouseGuests will move in to the Big Brother house, tying with Big Brother 4 for the largest number of HouseGuests in the series.

Have-Nots
As the Have/Have-not competition was replaced with Battle of the Block, the Head of Household must select 4 have-nots each week until Battle of the Block ends.