Channel 5 have confirmed that Brian, who entered the house two weeks ago as a legendary housemate for Time Warp week, has quit the show.
Producers have not given a reason for his exit.
The legendary housemates - Brian, Helen Wood and Nikki Grahame - entered the house as part of a task this month. Originally staying in a secret bunker with Marc O'Neill, the legendary housemates watched all the house action and decided who would face eviction for the forthcoming week.
In the past week, viewers have seen Brian embroiled in heated arguments with Helen, and he even threatened to walk before Big Brother persuaded him to stay.
The legendary housemates were originally supposed to stay in the main house for a week, but on Friday, Big Brother said they would be staying put for a little while longer.
Brian - who originally won Big Brother in 2007 - was also involved in a romance with housemate Jade Martina Lynch.
Tonight's episode of Big Brother at 10pm will detail Brian's departure.
Speaking to Brian before he entered the house, he told Reveal: "It's very surreal but I'm really excited now. I had a lot of nervous energy and I've been so nervous. I thought, 'I don't think I can do it', but now I'm here, and now I'm at Elstree... it just feels like coming back home in a weird way.
"I just hope that when I leave after that week that I can leave with a good experience of it. I'm still a huge fan of the show."
He added: "I've done it before and I had a good experience from it and eight years later, people are still nice to me. I didn't want to go in there and have something bad happen, as it would just change the landscape for the rest of your life, really. That was the only thing. But at the same time, I thought to myself, 'It was a risk the first time round and I suppose I'm a bit of a risk taker'. I'm a sucker for punishment!"
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