First in was financial sales rep Josie, 25, from Bristol.
“I don’t feel like any cameras are watching me, do you?” she asked second contestant, ex-serviceman Steve, 40, of Leicester, as he entered the house.
Presenter Davina McCall told viewers at the start of the show: “Don’t be sad because over the next 13 weeks we’re going to go out with an almighty bang.”
The contestants entered the house from a shortlist of more than 80 hopefuls who were at the Big Brother studios.
They only found out they were going into the house when their names were read out live on air.
Steve, who lost both of his legs and an eye when he was injured by a bomb while on patrol in Belfast, said he had found entering the house “totally surreal”.
Self-proclaimed “posh boy” Ben, a 30-year-old broadcaster and writer, meanwhile, said: “Abandon hope all ye who enter here. It feels very strange.”
Fourth in was professional Beyoncé lookalike Rachel, 23, from Nottingham, who also works as a hairstylist.
“I am a bit lazy when it comes to cooking,” she said on her recorded introduction. “If I never learn then people will do it for me.”
Twenty-five-year-old “Jack the lad” Nathan, a trainee joiner from Bingley, West Yorkshire, told McCall he had “the finest ‘monobrow’ in the western hemisphere”.
Christian minister David, 39, from Pontypool — who was wearing monk’s clothing — was booed as he entered the house.
“I’m not out to convert everyone to Christianity, I just am who I am,” he said. — BBCOnline.
Seventh housemate Caoimhe, a 22-year-old student from Dublin, was also booed, while voluntary worker Govan was cheered by the crowd as his name was announced.
The 21-year-old ran straight to the toilet as soon as he entered the house.
Film-maker Shabby, real name Keeley, was also booed as she sprinted in.
The 24-year-old, who lives in squats in London, screamed: “This is nuts, get me a drink.”
Tenth contestant Ife, 25, a professional dancer from Milton Keynes, Buckinghamshire, who has worked with Cheryl Cole, was followed in by 24-year-old vehicle body builder John, from Melbourne in Australia.
“I guess they like what I look like,” John said when asked what women liked about him.
Sunshine – real name Yvette – said in her recording: “I told my dad my car had broken down so he would buy me a new one and he did.”
The medical student, 24, from Peterborough, Cambridgeshire, struck a pose as she entered the house before kicking her shoes off.
Retail assistant Corin, 29, from Stockport, Greater Manchester, who says she looks like model Katie Price, rejected the crowd’s boos saying: “I don’t care. I’m going in. I’m buzzing.”
The inevitable twist came towards the end of the show when a final name from the pool of possible contestants was picked out in a tombola.
Unemployed 28-year-old Mario, from Essex, was selected by McCall and was told to put on a giant mole costume.
As the Big Brother mole, he will be asked to perform “a series of dastardly deeds” against the other housemates.
If they guess he is behind any of the deeds, he will be evicted.
The new housemates have been confronted by a brightly decorated, circus-themed compound, where there will be less privacy than ever before.
It was announced earlier that, after the winner of Big Brother 11 is decided, he or she will be joined by a number of ex-contestants for a further two weeks.