The show was always vague about who he was -- his name may have been Spender, he may have been Mulder's father, and he may have killed JFK, but all we know for sure is that he was one evil dude. You can tell from the cigarette.

Why We Almost Didn't Get Him:

It's true that he was there from the beginning -- the Smoking Man appeared in the first scene of the pilot episode -- but he didn't appear again until the last scene of the Season 1 finale. In neither scene does he have a speaking role. That's some ominous-as-s**t foreshadowing!

Fox
That's why we've shivered at every job interview since '93.

Except that it wasn't. The Smoking Man was an extra, known in the script only as, you know, "the Smoking Man." His entire purpose was just to stand around in the background whenever the writers wanted to remind the audience that Mulder and Scully were being watched by somebody. If you don't know what we mean, go look at the IMDb page of the actor, William B. Davis. Before his 1993 casting in The X-Files, he was playing roles that didn't even get actual names -- he played "Judge" in an episode of MacGuyver, "Doctor" in one episode of Nightmare Cafe, and "Lawyer" in the TV movie Omen IV: The Awakening. And who could forget his work as "Inspector #2" in that one episode of Wiseguy?

So why would the producers of The X-Files declare this random background actor to be the central villain of the show's overarching storyline involving alien beings, government coverups, and unresolved subplots? They even did an entire episode joking that Cigarette Smoking Man was behind pretty much every terrible world event of the last 40 years. The answer is that the writers never intended for that to happen at all.

Fox
Another conspiracy sadly debunked.

As we've pointed out in the past, the central plot of the show was more or less made up as it went along. It was only when Gillian Anderson got pregnant and took a partial hiatus from the second season that the writers needed to introduce new characters to make up for her absence. Davis was given a speaking role for the first time, and that's when the creators of the show suddenly realized, holy s**t, he can actually act. They had stumbled across an iconic Hollywood villain by getting lucky with their extras casting.

Likewise ...

Why We Almost Didn't Get Him:

The character was introduced to the show in typical Lost fashion, mysteriously appearing on the island out of nowhere halfway through Season 2, telling a highly implausible story about how he had crashed while on a round-the-world hot air balloon trip. By the end of his three-episode story arc, everything he said was revealed to be a lie, and he ended the season having taken three of the main characters hostage. Come Season 3, he's the scheming villain the audience is tuning in to see.

ABC
Will he kill your favorite character? Will he kill your favorite bunny? Stay tuned to find out!

But those few episodes in Season 2 were supposed to be it -- that's all the actor was signed up for. Like The X-Files, the twists in Lost were pretty much invented as the writers went along, and at that stage the producers just wanted a creepy-looking guy to show up on the island and set up the cliffhanger for next year. They kept him around because they liked how Michael Emerson played Ben, and Emerson originally agreed to do it because, well, we'll just quote the DVD commentary:

Lost Writer Carlton Cuse: "I remember we got on the phone with Michael, and it was funny, because it was ... a sort of slushy day in New York. And he was walking along the street, and we were, like, 'Want to go to Hawaii for a couple of episodes?'"

Michael Emerson: "Yes."

Carlton Cuse: "There wasn't even a pause. There wasn't even a hesitation. It was like, 'Absolutely.'"

Michael Emerson: "Yeah, it was snowing in New York."

Damon Lindelof: "It was the easy sell."

ABC
They showed him a still from the pilot. He says he didn't notice any plane wreckage.

So there you go: Ben Linus would never have become a Big Bad on the show if he'd been played by somebody who didn't bring the "creepy genius" vibe like Emerson, and Emerson may not have done it if it had been a nicer day in New York.

And as with Cigarette Smoking Man, he took a pretty one-dimensional stock villain and elevated him with a creepy "What is this f**ker going to do next?" energy that viewers couldn't stop watching. Without them, both shows probably couldn't have stumbled ahead for so long after they jumped the shark.

If we ask you to name some characters from Sesame Street, you're likely to say Big Bird, Kermit, and Elmo. And of the three, Elmo is both the newest character and the most popular. Since exploding onto the scene, he has testified before Congress, and his Tickle Me Elmo doll was so popular that adults paid thousands and gave each other concussions to get their hands on it. In 1998, the show's producers finally surrendered to him and cut 15 minutes from each episode to give Elmo his own closing segment. They kept making the segment for more than a decade, until they decided to phase it out ... in favor of an Elmo musical.

Sesame Workshop
Chicks dig a pimpin' singing voice.

People can't get f**king enough of Elmo, is what we're saying.

Why We Almost Didn't Get Him:

Elmo didn't start out as a character at all. He was one of dozens of random, nameless "monster" Muppets that Sesame Street kept lying around in case they needed a crowd scene. Here he is in an early appearance, with the voice he had before he gave up his three-pack-a-day smoking habit.

He wasn't enough of a character back then to even have a name or a fixed voice, but he was colloquially referred to as "Baby Monster." Later he appeared with the voice of an aging female casting agent in a sketch that we're sure is hilarious to 5-year-olds.

Even a career stuck in the background would have been fine compared to what the next puppeteer, Richard Hunt, wanted for him. Hunt put his own spin on the character -- this time, a gruff caveman voice -- but he hated Elmo. He'd drag the Muppet around like a mop, and he'd literally shout, "I hate this damn puppet! I'm suffering with it."

Then, one day, he physically threw the puppet into the lap of a random junior performer -- Kevin Clash, who voiced such memorable characters as, uh, Dr. Nobel Price and Ferlinghetti Donizetti. But when Clash stuck his hand into Elmo, it was like Frodo putting on the One Ring. Avoiding the various deep, throaty growls that people had been trying to force on Elmo, Clash tried an ear-shattering falsetto and immediately struck gold.

Bryan Bedder/Getty Images
He uses the same voice when he's angry at traffic.

Unfortunately, in 2012, Clash wound up the subject of a Michael Jackson-esque series of child sex allegations that, while thrown out of court, led to Clash's resignation from the show. In seeking to replace the puppeteer, Sesame Street wisely found someone who could replicate the voice instead of taking the opportunity to reinvent Elmo as a rapping pirate or something.

The show won the Best Drama Emmy four years running (tied for the most ever), presumably due to its central lead. The character arguably had a good shot of winning the real-life 2008 elections, even though he was fictional and constitutionally barred from a third term.

Why We Almost Didn't Get Him:

The drama set in the White House and covering the presidency originally wasn't going to include the president at all.

The show was supposed to focus on the president's staff (and it largely ended up doing so), covering the public relations side of the presidency. Aaron Sorkin thought the presence of the executive himself would ruin the show's status as an ensemble drama. So policy and political machinations would be discussed and responded to by everyone relevant -- other than the president himself.

NBC
The White House Janitor, played by Charlie Sheen, was to be a regular sounding board for drug policy.

Of course, they couldn't ignore the president entirely, that would just be ridiculous. The initial plan was for the audience to catch occasional glimpses of the president, just a bent-over ass or the back of his head. But as this was the same gimmick they used on Home Improvement to hide Wilson's face, it wasn't too difficult to figure out how silly that was going to look.

So they grabbed Sheen. He was basically a stock presidential actor, thanks to his various White House acting gigs, so they just brought him in for the pilot and occasional appearances thereafter. You can watch the pilot and see that he plays a pretty minor part for such a major role. Soon after filming, everyone realized that the president popping in once every month wasn't much better than not appearing at all. They broke down and rewrote him as the lead.

NBC
Sparing us such arcs as "intern's daughter kidnapped" and "Deputy Communications Chief assassination attempt."

Sheen was keen to take on the role, because whether or not TV can really convince anyone of anything, it proved a great way for the social activist to at least get people talking about his favorite issues. After a couple years, NBC was actually afraid that his outside soapboxing would hurt the show, but what could they do? Try to make the show without him? That would be insane.

You may be thinking, "How were they going to write Frasier out of a show called Frasier?" But people often forget that the star of that sitcom about rich people originally began as a character on Cheers, that sitcom about drunk people. Despite TV execs being generally starved for originality, spinoffs are rare in TV land, and popular spinoffs virtually unheard of (we're looking at you, Joey).

CBS
Only occasionally is a spinoff universally loved, like The Brady Brides.

But Frasier was so popular that he not only got his own show for 11 seasons, but also showed up on another sitcom called Wings, because why not?

Why We Almost Didn't Get Him:

Frasier Crane (Kelsey Grammer) was never originally a core cast member of Cheers. In fact, he was only supposed to show up for a few episodes in the third season, long enough to have an affair with Diane (Shelley Long) and create a little dramatic tension. Essentially, he was a device to make Sam jealous.

Moviestore Collection/Rex Features
He began as a minor villain, yessiree bob. A sideshow.

Of course, Sam, Ted Danson's bartender character, was the guy we were really supposed to like. He was the down-to-earth, friendly, relatable lead. Frasier Crane was basically his opposite -- a stuffy, pompous rich guy who didn't care much for the working class functional alcoholics who hung around at Cheers. The plan was that he would stick around for a few days until the others told him to piss off and Diane could come to her senses.

And no one was more eager for this to happen than Long, who hated Grammer and was constantly demanding he be written out of the show as quickly as possible. But you know who hated Long in return? The writers, who Grammer says kept the character around purely out of spite. If Long had liked him, or even been less of a horrible person, maybe they'd have just let Frasier drop off the map. Of course, that might be Grammer not giving himself enough credit -- the producers say they just loved what Grammer did with the character, which is what they would say since it sounds better than "The entire show was just our experiment to see if we could cause Shelley Long to have a nervous breakdown."

NBC
When they gave her a guest spot on Frasier, the experiment ended in success.

Regardless, between Cheers and its spinoffs, the one-time character that nobody was supposed to like became the longest continuously running television character of all time. And we are counting X-Men 3 as a Cheers spinoff here, because the Beast was clearly Frasier Crane in a blue furry costume.

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Related Reading: Knowing more about your favorite characters isn't always a good thing. Mrs. Piggy's guest appearance as a cannibal sure wasn't heartwarming. And James Bond seems a little less awesome when you hear about Sean Connery's desire to murder him. That sort of behavior isn't limited to actors, plenty of musicians despised their most iconic songs.