Former Big Brother winner Brian Belo vowed to bring "carnage" to the house as he dramatically rejoined the show.
Belo, who arrived with ex-housemate Nikki Grahame and former winner Helen Wood, said he wanted to bring the Marbella pool party lifestyle to the Channel 5 show.
The three housemates have entered a secret bunker, where they will stay until they go into the main house on Sunday.
They joined housemate Marc O'Neil who was evicted last night, only to be told it was a fake and he would be spending a few days in the secret bunker.
Wood, who reportedly had an affair with England footballer Wayne Rooney, said she was delighted to be returning to the show which she won last year.
It was one of the most complained about shows of 2014, with 3,784 viewers objecting, many of them about Wood who was accused of bullying other contestants.
But speaking ahead of her comeback, she said she did not feel anxious about taking on the series again: "Not at all, get me in there now, get me out of reality.
"I'd go back every year if they'd have me."
Belo is best known for asking fellow housemates "who's Shakespeare?" while appearing on the show in 2007 and triumphed in the final with 60% of the vote.
But this time round, Belo has swotted up on his literature and was inspired to return when someone his own age - 27 - won the show in Australia.
He told the Press Association: "I only knew about this at 6pm on Monday evening, only agreed to it Tuesday afternoon - I've never known anything to happen this quickly.
"Big Brother is like a home away from home. I need to remember to just enjoy it, I'm more grown up and I've scratched up on my literature this time, so I know who Shakespeare is.
"I have been watching the Australian Big Brother and the guy that won it was 27, which is the same age as me, and I wondered what would it be like for me to be in there in my mid-20s."
Belo added he had missed the smell of the house and planned to go to bed later during his latest stint on the show.
He said: "I want to have some partners in crime and cause some havoc, I mean really cause some carnage.
"We have to get everyone round the swimming pool, I want to bring Marbella to Big Brother and tear the roof off the place.
"This is a once-in-a-lifetime opportunity and if I can see the housemates holding back, I'm going to try to get their core beliefs and bring them out."
Following his Big Brother victory, Belo had a starring role in Harry Hill's TV Burp and he even performed Shakespeare scenes in Stratford-upon-Avon in 2008.
He said he was excited at the prospect of entering the house with Grahame, saying he considered her a "good mate".
Grahame , 33, stood out in the 2006 series of Big Brother for her temper tantrums, even coining the catchphrase "Who is she?!" which she shouted in outrage in the Diary Room about fellow contestant Susie Verrico. She also had a short-lived romance with eventual winner Pete Bennett.
After leaving the house she got her own show, Princess Nikki, which ran on E4 for six weeks in 2006.
Grahame, who has spoken publicly about her battle with anorexia, returned to the house for Ultimate Big Brother in 2010, meaning this is her third time on the show.
Wood said she would be happy to return to the show every year: "I came out of the house, I thought everyone was my friend, which was really embarrassing and naive of me and really cringe because no one was my friend.
"I said I'd never do that experience ever again because it would tarnish what I'd already done and it was a once-in-a-lifetime thing.
"Bollocks to that. I'd go back every year if they'd have me."
Asked what was the most difficult thing about being in the Big Brother house, she added: "Nothing. Do you know what, it was an absolute walk in the park.
"So many people find it really difficult, but I find it really easy. You learn how to socialise with people without a telephone. People who are obsessed with phones I don't think would cope with it, but I love not having a phone and testing my ability of being able to speak to people.
"I like being this little lab rat - you're being experimented on and it's good to test yourself. It's a good place to find yourself. I've changed an awful lot since Big Brother."