Ellen DeGeneres in Friends? The TV castings that might have been

Ellen DeGeneres reportedly turned down the role of Phoebe Buffay on Friends. Photo / AP

Paul Hollywood was a silvery whisker away from never having a TV career. When BBC Two first commissioned The Great British Bake Off in 2009, after programme makers Love Productions had been trying to sell the idea for four years, the corporation happily agreed to cast Mary Berry as the contest's judge. However, the corporation wanted her sidekick to be Tom Herbert.

Who? Well, quite. Alongside sibling Henry, he formed half of the Fabulous Baker Brothers, who were all the rage back then. Tall, dark, handsome and bearded, he's a sort of younger, hipper Hollywood.

After screen tests, though, Berry's strong preference was for Merseyside-born master baker Hollywood. They not only clicked personally but she believed his bread expertise balanced her background in patisserie. The doyenne of dough got her way. The corporation relented. Eleven years later, Hollywood is a household name and, as the only constant in Bake Off's line-up, the show's unofficial custodian.

The annals of TV history are full of such stories - nearly-weres, might-have-beens or didn't-quite-work-outs. It makes for a sort of fantasy parallel world, where our favourite programmes are populated by entirely different faces.

Another BBC contest, The Apprentice, is a case in point: in 2004, when producers were looking for a frontman, Alan Sugar was only fourth on their shortlist. The initial choices – fashion magnate Sir Philip Green, media mogul Felix Dennis and Ryanair CEO Michael O'Leary – all declined; a lucky escape for the BBC, some might say, especially in the case of Green.

And there is a scenario in which The Graham Norton Show might have been hosted by Jenny Eclair, of Grumpy Old Women fame. In 1997, it was Eclair to whom Channel 5 first turned when the host of its successful talk show, Jack Docherty, went on holiday. Eclair had booked a residency at the Edinburgh Fringe, so couldn't provide cover, allowing Norton to deputise instead. He proved so popular with viewers that Channel 4 offered him his own vehicle. So Norton was a hit and, in turn, he was poached by the BBC. The rest is chat show history.

Gillian Anderson nearly scored the role of Lady Grantham in Downton Abbey, but lost out to Elizabeth McGovern. Photos / Getty Images / Supplied

Of course, it's in drama and sitcom where near-misses most often occur. Actors might get approached, auditioned or even cast, before changing their minds or dropping out due to diary clashes. Sometimes they're replaced by a rival and it proves a career-changing cultural moment.

Matt Smith almost became Dr John Watson in Sherlock but showrunner Steven Moffat thought his "barmy energy" was too close to Benedict Cumberbatch's. "It was like having two Sherlocks in the room," said Smith. Martin Freeman nabbed the Watson role instead. But it wasn't all bad news for Smith; the following year Moffat cast him as another Doctor - the Timelord's 11th incarnation in sister show Doctor Who.

There are also cases where actors have filmed entire episodes before being dropped. Actress Elizabeth Shepherd was The Avengers' first Emma Peel but, after shooting two instalments, producers realised there was no chemistry between her and co-star Patrick Macnee. Relative unknown Diana Rigg was brought in. Sparks flew.

The

218cm Richard Kiel, best known as henchman Jaws from two James Bond films, was hired as The Incredible Hulk for the 70s series. After the first week's shooting, it was deemed that although he had the towering height, Kiel lacked the muscular physique needed for the destructive green beast. Some said Marvel Comics made the call. Others claimed a boy on set took one look at Kiel and said he didn't look strong enough to be The Hulk. Either way, bodybuilder Lou Ferrigno took over.

Channel 4 filmed several episodes of Shameless with actor Sean Gallagher before acknowledging that, despite his surname, he was too young to convince as the booze-sodden patriarch Frank Gallagher. David Threlfall, 12 years his senior, stepped in, reshot his scenes and made the role his own.

Meanwhile, the producers of fantasy epic Game of Thrones originally cast Tamzin Merchant and Jennifer Ehle as Daenerys Targaryen and Catelyn Stark respectively, only to swap them out for Emilia Clarke and Michelle Fairley after a disastrous unaired pilot.

They also came close to casting Iwan Rheon as heroic Jon Snow, before recasting him as Ramsay Bolton, one of Westeros's most despised villains. As he later admitted: "They made the right choice. It would've been a very different Jon Snow if I'd played him."

Henry Cavill missed on Robert Pattinson's role in Twlight - and got down to the final two in Bond. Photo / Getty Images

Indeed, US box-set drama is the source of some intriguing might-have-beens. Ray Liotta, best known for his starring role in the gangster flick Goodfellas, was offered the lead role in HBO saga The Sopranos, but decided to pass, fearing he'd be forever typecast as a mafioso.

Similarly, Matthew Broderick and John Cusack were approached to play teacher-turned-drug lord Walter White in Breaking Bad. Both balked at being such a monstrous bad guy – leaving the lesser-known Bryan Cranston to deliver an indelible performance across five series.

Would all these shows have been as successful with different stars? We'll never know, but it's a diverting parlour game to ponder.

The most unlucky man in Hollywood is probably Henry Cavill who narrowly missed out on Twilight and got down to the last two for James Bond when that franchise was looking to replace Pierce Brosnan. As some consolation, Cavill went on to don Superman's cape in three blockbusters.

"Regrets are something you can't really have as an actor, because ultimately you'll destroy yourself," Cavill has said. "There's a lot of disappointment in this business." Denzel Washington (almost cast as Tubbs in 80s phenomenon Miami Vice) puts it more succinctly: "If you pray for rain, you've got to deal with the mud too."

That certainly applies to a long string of actors in US comedy. The part of pompous psychiatrist Dr Frasier Crane on Cheers was written with John Lithgow in mind but he passed because "at that point in my career, episodic television was beneath my dignity".

The iconic Friends cast was reportedly going to be very different. Photo / Supplied

Friends trio Rachel, Joey and Phoebe (now inseparable from actors Jennifer Aniston, Matt LeBlanc and Lisa Kudrow) were originally offered to Vince Vaughn, Jane Krakowski and Ellen DeGeneres respectively.

Across Manhattan, House's Lisa Edelstein came so close to landing the role of Sex and the City's Carrie Bradshaw that a contract was drawn up - until Sarah Jessica Parker said yes too. Edelstein found it "too painful" to ever watch the show after she missed out.

Carrie's friend Miranda, meanwhile, was originally offered to comedian Sandra Bernhard, who demurred due to the "terrible script" - luckily for Cynthia Nixon, who stepped into her Manolo Blahniks. Showbiz is a fickle trade - and so is shoebiz.

5 TV turns that might have been

Gillian Anderson in Downton Abbey

She's about to portray Margaret Thatcher in The Crown but Anderson was originally offered another British period saga - the role of Downton matriarch Lady Grantham, which instead went to Elizabeth McGovern.

Martin Landau in Star Trek

He almost became pointy-eared Spock but Landau didn't take the role because, "a character without emotions would drive me crazy. I'd have to be lobotomised." Leonard Nimoy boldly went there instead.

Paul Giamatti in The US Office

Giamatti was offered the lead in the US reboot of The Office but fresh from the success of Oscar-winning film Sideways, turned it down. It became a surprise hit and made a star of his replacement, Steve Carell.

Pamela Anderson in The X Files

Creator Chris Carter had the Baywatch bombshell in mind when writing the part of Agent Scully but Fox execs said she wouldn't convince as a paranormal investigator. Another Anderson, Gillian, got it instead.

David Tennant in Hannibal

Mads Mikkelsen starred as the cannibalistic killer in the TV spin-off from the Hannibal Lecter novels - but

David Tennant had several meetings with NBC and came close.