The fifth season of the Australian reality television series, Big Brother, also known as Big Brother 2005, began on 8 May 2005, with housemates going into the House the day before, and finished on 15 August 2005, lasting 101 days. The season was aired on Network Ten in Australia, and TV-2 in New Zealand with a four-week delay. Promos for the show suggested that Big Brother would be different this year, and phrases such as "Assume Nothing, Expect Anything", "Let's Play" and "Think Again" were used throughout the series, especially during Opening Night. The winner was announced on the finale that was watched by 2.282 million Australian viewers.

The theme for this season was "single, sexy and competitive". Auditions for housemates were held in March 2005. In a departure from usual procedure, candidates were not required to send in videos of themselves as had been the case for prior auditions. Instead, the producers toured major Australian cities and conducted interviews. They searched for attractive singles that were willing to have sexual relations on camera. The fifth season marked a noticeable change in the portrayal of 'Big Brother'. Compared to earlier seasons, the voice, provided by Nick Colquhoun, adopted a much stricter and more authoritarian tone, often described by viewers as "evil". During this season, Big Brother frequently imposed fines and penalties on housemates for rule breaches, reinforcing a tougher approach to house discipline. This stricter style and vocal delivery continued in the following two seasons, with Big Brother maintaining the same stern tone and enforcement of rules throughout the 2006 and 2007 series.

The season came under controversy after viewers complained about nudity and sexual acts shown on 'Uncut'. Communications Minister Helen Coonan asked the Australian Broadcasting Authority (ABA) to investigate whether Uncut complied with the TV industry's code of practice. It was later found that Network Ten breached the code of practice but no direct punishment was imposed by the Australian Communications and Media Authority (ACMA).

Changes and additions

Fines On Opening Night, it was revealed that A$5,000 would be subtracted from the $1 million prize money every time the housemates broke a rule. Such rules included discussing nominations, which must remain secret, not giving adequate reasons for nominating, and forgetting to wear microphones at all times. Michelle was known for being the housemate to get the most such fines—$60,000. Geneva had the least amount of fines $15,000, two in the early days at the house and one near the end of her eviction.

The Logans

It was revealed that twins would be entering the House, regularly changing places without the other housemates knowing—this was a twist first used on the fifth American series of Big Brother. Greg and David entered the House as a single person named Logan (their shared middle name). Their task was to remain undetected for two weeks while swapping places at Big Brother's command, and as a reward, they would participate as separate housemates. The secret of the twins was discovered one week into the series by housemate Glenn, and this was revealed during Lies Exposed.

As a result, both Logans were able to continue living in the House, but would be treated as a single person in matters such as evictions and nominations. Late in the series, a special eviction was held where one twin was evicted based on the votes of the other housemates, and the remaining twin was allowed to continue in the House as a normal housemate. During this eviction process, David was evicted. However, because Greg was voted the winner, both David and Greg shared the prize equally.

Housemates Name Age Day entered Day exited ResultLogan Greg Mathew 23 0 100 David Mathew 23 0 74 Tim Brunero 27 0 100 Vesna Tosevska 27 25 99 Melanie Smerdon 19 53 92 Kate Benson 21 085 Christie Mills 19 0 78 Rita Lazzarotto 29 53 78 Dean Glucina 24 0 71 Simon "Hotdogs" Deering 27 0 64 Heath Tournier 20 53 59 Glenn Dallinger 21 0 57 Geneva Loader 19 0 50 Rachael Burns 21 25 43 Michelle Carew-Gibson 24 0 36 Michael Farnsworth 27 0 29 Gianna Pattison 24 0 22 Angela Aiken 29 0 15 Constance Hall 21 0 10 Nelson Russell 23 0 10 Notes

Friday Night Live themes and winners Week Theme Winner Runner up 1 Romans Glenn Logan David 2 50's Gianna Tim 3 Wacky Athletics Michelle Hotdogs 4 Italy Rachael Tim 5 Country Fair Glenn Christie 6 Nautical Dean Rachael 7 Boot Camp Kate Tim 8 Asian Logan Greg Heath 9 Life in Space Logan David Christie 10 Winter Wonderland Logan Greg Christie 11 DIY Tim Melanie 12 Australian Tim Logan Greg 13 Mad Max All Star Team Housemate Team 14 Prize Fight Housemates won $236,000/$400,000

Nominations table Color key:

Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12 Week 13 Week 14 Nominationpointsreceived Fake Nominations Twin Eviction Day 99 Finale FNL Winner (none) Glenn Gianna Michelle Rachael Glenn Dean Kate Logan(Greg) Logan(David) Logan(Greg) (none) Tim Tim All-Starswon $20,000 Housemateswon $236,000 Greg 2-in-1 connection with David(Days 1–74) Nominated 2–Vesna 2–Vesna Nonominations Winners(Day 100) 6 Tim Nonominations 2–Angela1–Gianna 2–Geneva1–Dean 2–Dean 2–Dean 2–Dean1–Christie 2–Dean1–Geneva 2–Dean 2–Kate1–Dean 2–Dean 2–Rita1–ChristieDavid 2–Melanie1–Vesna 2–Vesna1–Greg Nonominations Runner-up(Day 100) 21 Vesna Not inhouse Exempt 2–Dean1–Geneva 2–Geneva1–Logan 2–Dean1–Logan 2–Kate1–Logan 2–Logan1–Dean 2–Rita1–Logan Greg 2–Kate1–Greg 2–Greg1–Tim Nonominations Evicted(Day 99) 32 Melanie Not inhouse Exempt 2–Logan1–Rita 2–Rita1–LoganDavid 2–Vesna1–Tim 2–Vesna1–Tim Evicted(Day 92) 6 Kate Nonominations 2–Tim1–Geneva 2–Gianna1–Geneva 2–Dean1–Tim 2–Hotdogs1–Christie 2–Rachael1–Christie 2–Vesna1–Hotdogs 2–Glenn1–Dean 1–Vesna 2–Rita1–Christie 2–Rita1–Christie Greg 2–Greg1–Vesna Evicted(Day 85) 27 Christie Nonominations 2–Tim1–Michael 1–Dean 2–Tim1–Michael 2–Michelle1–Kate 2–Rachael1–Vesna 2–Hotdogs1–Vesna 2–Dean1–Hotdogs 2–Kate1–Hotdogs 2–Kate1–Tim 2–Rita1–Kate David Evicted(Day 78) 24 Rita Not inhouse Exempt 1–Kate 2–Kate1–ChristieDavid Evicted(Day 78) 15 David 2-in-1 connection with Greg(Days 1–74) Nominated Evicted(Day 74) N/A Logan(Greg & David) Nonominations2–Christie1–Geneva2–Gianna1–Michelle2–Geneva1–Michael2–Michelle2–Geneva1–Vesna 2–Kate2–Kate1–Vesna2–Vesna1–Kate2–Vesna1–Rita 2-in-1 connection ended(Days 74)12 Dean HoldingRoom Nominated 2–Gianna1–Tim 2–Christie1–Michelle 2–Michelle1–Tim 2–Rachael1–Vesna 2–Vesna1–Tim 2–Vesna1–Christie 2–Tim1–Vesna 2–Tim1–Rita Evicted(Day 71) 31 Hotdogs Nonominations 2–Geneva1–Angela 2–Michael1–Geneva 2–Christie1–Michael 2–Michelle1–Christie 2–Rachael1–Glenn 2–Geneva1–Glenn 2–Kate1–Christie 2–Kate1–Tim Evicted(Day 64) 31 Heath Not inhouse Exempt Evicted(Day 59) N/A Glenn Nonominations 2–Geneva1–Gianna 2–Hotdogs1–Geneva 2–Christie1–Dean 2–Geneva1–Dean 2–Christie1–Geneva 2–Hotdogs1–Vesna 2–Kate1–Christie Evicted(Day 57) 10 Geneva Nonominations 2–Michelle1–Hotdogs 2–Hotdogs1–Gianna 2–Glenn1–Dean 2–Glenn1–Kate 2–Rachael1–Hotdogs 2–Vesna1–Hotdogs Evicted(Day 50) 29 Rachael Not inhouse Exempt 2–Geneva1–Logan Evicted(Day 43) 10 Michelle Nonominations 2–Angela1–Gianna 2–Michael1–Dean 2–Dean1–Michael 2–Hotdogs1–Logan Evicted(Day 36) 16 Michael Nonominations 2–Michelle1–Hotdogs 2–Hotdogs1–Gianna 2–Glenn1–Logan Evicted(Day 29) 10 Gianna Nonominations 2–Tim1–Geneva 2–Geneva1–Michael Evicted(Day 22) 12 Angela Nonominations 2–Michelle1–Gianna Evicted(Day 15) 5 ConstanceHoldingRoomEvicted(Day 10) N/A Nelson HoldingRoom Evicted(Day 10) N/A Notes 1 2 none 3 none 4, 5 none 6 7 none 8 Nominated(pre-twist) (none) Geneva,Michelle,Tim Geneva,Gianna,Hotdogs Christie,Dean,Glenn,Michael Christie,Dean,Hotdogs,Michelle Christie,Dean,Geneva,Rachael Geneva,Hotdogs,Vesna Christie,Dean,Kate Hotdogs,Kate,Tim,Vesna Kate,Logan,Rita All Housemates (none) Greg,Melanie,Vesna Greg,Tim,Vesna (none) PowerOutcome Michelle Gianna Glenn Christie Dean Geneva Christie Tim Logan No Immunity Greg Tim Againstpublic vote Constance,Dean,Nelson Angela,Dean,Geneva,Tim Geneva,Gianna,Hotdogs,Michael Christie,Dean,Michael Dean,Hotdogs,Michelle Christie,Geneva,Rachael Dean,Geneva,Hotdogs,Vesna Dean,Glenn,Hotdogs,Kate,Vesna Heath,Melanie Dean,Kate,Rita,Tim AllHousemates David,Greg Kate,Melanie,Vesna Greg,Melanie,Vesna All Housemates All Housemates Hotdogs,Kate,Vesna EvictedNelson52%to evict Angela41%to evict Gianna53%to evict Michael48%to evict Michelle41%to evict Rachael47%to evict Geneva31.3%to evict Glenn49%to evict HeathAustralia’s choiceto evict Dean52%to evict Rita35%(out of 7)to evict David4 of 6 votesto evict Kate56%to evict Melanie59%to evict Vesna39%to evict Tim55%to evict Constance32%to evict Hotdogs53%to evict Christie39%(out of 6)to evict Greg45%to evict

Notes

: As punishment for lying during the audition process, Constance, Dean, and Nelson were fake evicted and sent to the Holding Room. Believed to have been evicted, they could not be nominated by their housemates. On Day 9, they were informed that all three of them would be facing Australia's vote in a Special Eviction. Unbeknownst to everyone, this was also a Double Eviction. : Dean was nominated alongside nominees Angela, Geneva and Tim as a result of his previous rule break (see note 1). : As new housemates, Rachael and Vesna were exempt from nominations and could not nominate or be nominated. : As new housemates, Heath, Melanie and Rita were exempt from nominations and could not nominate or be nominated. : On Day 59, the Intruder Eviction was held - first, the housemates had to decide by consensus which of the three intruders they wanted to keep in the house. They saved Rita. Heath and Melanie then faced Australia's vote to determine the Intruder to be evicted over a 20 minute vote. Heath was evicted. : Week 10's nominations were fake, and it was revealed after voting that all housemates were nominated. In place of the Three-Point Twist, the Friday Night Live winner, Greg, was given a 50-50 chance to earn immunity by random choice for himself & David. The Logan twins were given two boxes, containing "Not Nominated" and "Nominated" cards, and told to select one box. They selected the "Nominated" box, leaving their nomination intact. While the Logans selected the box after Nominations, Greg (as the sole Logan remaining after the Twin-Eviction) only learned the outcome during the Sunday Eviction. : On Day 70, the housemates voted to evict one of the Logan twins in a special Twin Eviction. In the event of a tied vote, Australia would vote to evict a twin in a 5-minute vote. The surviving twin would represent both Logans, and the pair would share the prize money if they won. David was evicted. : All housemates faced Australia's vote in the final week; the housemate with the fewest votes to evict on the final night was declared the winner. A special eviction occurred on Day 99, in which Vesna was evicted after receiving the most votes to evict. Additionally, during the Final Weeks, the Friday Night Live was held with the Housemates competing as a team to win back lost prize money (the first against a team of Big Brother “All-Stars” and the second in which the housemates contested the games together); these games had no impact on the Nominations or Evictions.

Suitcase nominations On Day 0, each housemate was called to the diary room and asked to pick another housemate to not receive their suitcase for the duration of their time in the house. Constance had the majority and lost her suitcase. The voting went as follows: Housemate Voted for Total votes Angela Gianna 0 Gianna Nelson 2 Nelson Dean 1 Dean Kate 1 Christie Kate 1 Tim Michael 0 Glenn Hotdogs 0 Constance Gianna 4 Michelle Constance 0 Kate Constance 2 Logan Constance 0 Michael Constance 2 Hotdogs Michael 1 Geneva Christie 0

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