Big Brother Australia 2008 or Big Brother 8 was the eighth season of the Australian reality television series Big Brother Australia and was the final series to air on Network Ten.
The eighth season launched on 28 April 2008. A total 20 housemates competed in the series. Halfway through the series, the prize money was revealed to be $250,000, the amount originally given in the earlier season of the series.
Season 8 introduced Kyle Sandilands and Jackie O as the new hosts, replacing Gretel Killeen, who had previously hosted the show from Season 1. It also featured the return of an adult-themed weekly installment titled Big Mouth.
Auditions opened in late 2007. People wishing to audition were required to post a video audition of themselves on the official Big Brother website. Voting closed on 7 January 2008. The three people with the highest number of votes would be guaranteed a place in the House with the top 50 others to go through a second selection process.
The season featured a new audition process similar to the format used in the earlier seasons, where people wishing to audition sent in a tape rather than attending cattle call audition sessions. For the first time in Big Brother Australia history, the public could vote which housemates they wanted to see in the House before the start of the season.
Promotional advertisements for the new series premiered on 6 April 2008 featuring a short video of former Australian Prime Minister John Howard criticising the show in 2006, stating that Channel Ten should "get this stupid show off the air", followed by the tagline "I Don't Think So" from the eponymous Kelis track.
The series began Monday 28 April 2008 at 7:00 pm. The opening episode had the lowest-ever ratings of any launch of Big Brother Australia. The episode mostly outrated its competitors in most timeslots—except its second half-hour when it lost out to Border Security. The audience for the launch peaked at 1.91 million. The series lasted a total of 84 days. The 2008 finale aired on Monday 21 July 2008 at 7:00 pm on Network Ten. It was the first Big Brother Australia finale to feature three finalists and the first hosted by Kyle Sandilands and Jackie O.