[Eddie.]

As in when this housemate got evicted, the flow of the series changed drastically whether for the better or the worse.

BB2- Narinder. After her eviction the rest of the series revolved around only one prominent storyline (Paul and Helen), besides that BB2 after her eviction is generally a snoozefest.

BB4- Anosuka. Like what I have mentioned before if she had survived the first week eviction, she would have gone very far. She made that first week of BB4 and if she stayed then the series would have been much more tolerable to watch. Also she would have kept us entertained before Lisa came in.

BB7- Nikki's original eviction. I know that the likes of Sezer and Grace getting evicted impacted the series as well, Nikki's eviction sealed the fact that only certain housmates made BB7 a great series. From her original eviction to the time she got back Aisleyne and to an extent Susie, carried that series on their backs.

BB8- Charley. Her leaving on Week 8 made an entertaining series become a chore to watch. This is probably the biggest change of any of the series because after her eviction, the only constant storyline was Chiggy. But then obviously that didn't work out since Chanelle walked a few days after.

BB15- Danielle. 15 was already intolerable, but it was still a bit watchable until Danielle got evicted and really all we got after that was Helen's reign of terror which didn't really make pleasant television.

BB16- 4in4out evictions. While I thought Sam, Harry Amelia and Marc were worthy additions to the series, this stupid twist ruined the flow of what could have been a great series completely. Definitely the worst twist in BBUK history because it just didn't make sense and completely violated what Big Brother is supposed to be in the first place (a common theme that prevails throughout the series)

[Epic.]

per series
BB1: Nick
BB2: Narinder
BB3: Adele
BB4: Jon/Federico worst double eviction ever
BB5: Marco IN A GOOD WAY
BB6: Maxwell IN AN EVEN BETTER WAY
BB7: Nikki
BB8: Charley
BB9: None but for the sake of argument, Rebecca
BB10: Noirin
BB11: Ben
BB12: Rebeckah
BB13: Lydia
BB14: Callum
BB15: Danielle
BB16: Marc
BB17: Georgina
BB18: Sukhvinder
BB19: Lewis G

[Jigs]

CHARLEY UCHEA (plus Chanelle's subsequent walk)

Two of the biggest housemates that series leaving within days of eachother changed the season remarkably. Also, the following week was the Halfway House week so I remember thinking at the time that the series had changed drastically in such a short space of time.

[Daniel.]

3: Adele
5: Marco
6: Saskia
7: Grace
8: Charley
9: Jen
10: Kris (changed the course of team lisa being in control)
11:
12:
13: Lydia
14: Sallie
15: Toya
16:
17: Lateysha
18: Lotan if we count ejections, if not Chanelle
19: Lewis G

[CiaraNelly2000]

BB1: Nick
BB2: Narinder
BB3: ?
BB4: Anouska
BB5: Emma ejection or Marco evicfion
BB6: Saskia
BB7: Nikki
BB8: Charley
BB9: Bex
BB10: Noirin
BB13: Lydia
BB14: Sallie
BB15: Danielle
BB17: Lateysha
BB18: Lotan ejection or Imran eviction/sukh walking
BB19: Anamelia

[aaronneely2017]

Have not seen every series and will update this post when I've watched more.
Will not do every series as I feel there are certain ones were housemates exits have truly impacted the series.

Big Brother 2 - Narinder

Everyone that watches BB2 nowadays will definitely notice a decline in quality post Narinder's eviction and despite some funny quotes from Brian and the Helen and Paul love story that ish kept the series alive in some proportions. It's such a shame because the first half of this series is so good that losing Narinder would definitely lead to tragedy.

Big Brother 4 - Federico and Jon

I know many will always say Anouska should never have been evicted and her eviction killed the series but we never got to see enough of her to really know what she had to offer long-term, sure she was really nice, very flirtatious and seemed like one to speak her mind but in the end it has to be Federico and Jon's double eviction that impacted the series in the worst way. They were the only two characters left in that house that were actual good housemates (before lisa came in). With Jon we were losing the protagonist/ the big talking point of the show and Federico, the windup merchant and the antagonist (in a way). So with those two gone any chance of a conflict heavy/entertaining house was down the drain, thank goodness we got two weeks of our Lisa

Big Brother 6 - Maxwell

For the better!!! A lot of series can be known to have a house divide that can be very defining to the series. What I loved about the English vs Ethnics divide was that it was quite short but sweet and made way for the second-half to bring some new storylines i.e Pregancy scandal, Kemal's paranoia, Craig and Anthony, Orlaith wanting to walk, Science against everyone, and Kinga's epic return. Nevertheless English vs Ethnics has to be my all time favourite story line of all time

Big Brother 7 - Grace

Very difficult one, has to be either Nikki or Grace but I would have to say Grace mainly due to the fact that very early on we lost the series antagonist, Her downfall was quite lousy in retrospect would have been amazing to see her have a true downfall instead of being evicted from someone that was pretty much in theory part of the audience of the baying mob public that were screaming 'get grace out' It is definitly arguable to say Nikki's original eviction hurt the series but post Nikki I found to be great fun and really enjoyable and found that I could get to know the rest of the housemates a lot more without it being the Nikki show. (Dont get me wrong I love Nikki!) but there were still some fun moments like Automated Big Brother, Prison Task

Big Brother 8 - Charley

Not very surprising as Charley was the true saviour in a series that was lacking in good characters so her eviction clearly sealed the fate of the last 5 weeks were we were introduced to 4 out of 5 very forgettable halfway housemates to make up for the massive loss and Carole's everlasting iron fist reign over the house (is that a plus or a minus) Despite guru week seeing the fall of the Greek freak post Charley is not good.

Big Brother 18 - Lotan

Surpringly a housemate I have a lot of hate towards exit proved to be a negative rather than a positive for the series. The Rose Cottage/Thorn Cottage by Week 3 had reached boiling point as new resident Isabelle was introduced and the tensions in the house were intensifying by the day eventually leading into the infamous fight night 3 that saw Lotan chucked out of the house. Although a satisfying end to this scumbag, leaves me often questioning at the same time, that the series may still have been in need of Lotan moving forward a once we was ejected the divide became no more and what was introduced to us a second half of pretty inconsistent episodes. I don't think BB18 knew what it really was in that second half tbh. I still really enjoyed the series tho!

Will Update this once more series are complete