Deadpool owes his big screen success to a massive security failure

Deadpool is an enormous big screen success. In fact, Deadpool is such a success that you could argue it has completely subsumed Ryan Reynolds' on-screen persona. We're at a point now where it feels that almost every character he plays is a slight variation on the Merc with a Mouth.

Of course, this is all a mark of Reynolds' passion for the character. He was horrified by what 20th Century Fox did to the character in 2009 disaster X-Men Origins: Wolverine — turns out he's much less interesting without the mouth, who knew? — and wanted to right those wrongs. But it was only due to a leaked sizzle reel of test footage that he ever got that chance.

A year after Origins, writers Rhett Reese and Paul Wernick were hired to pen a solo movie for Deadpool. Tim Miller was later drafted in to make his directorial debut with the film. Then, in 2011, Green Lantern landed in cinemas to a critical and commercial raspberry of epic proportions.

Studio bosses, already spooked by the R-rated script for Deadpool, now lost confidence in Reynolds as a superhero leading man. They, however, did give Miller a small budget to make some test footage with Reynolds voicing Deadpool.

That footage didn't convince Fox to make the movie. At least, not yet.

Read more: Ryan Reynolds: I feel more free playing Deadpool than almost anything else (PA Media)

In 2014, the sizzle reel made its way online. Nobody is quite sure who leaked it, as far as we know, though Reynolds said in 2015 that he originally suspected Miller as the culprit. His working theory by then was that "someone recorded the footage on their iPhone and then released it". He said somebody then hacked into Miller's studio system and released the high-res version.

Watch: The leaked Deadpool test footage

Fans absolutely went wild for the sizzle reel. They were thrilled that a version of Deadpool true to the comics could be made, but furious at 20th Century Fox for not giving it the formal green light. The power of the fan base had spoken.

The footage leaked in July 2014 and, by September, Fox had announced that the Deadpool movie would move into production ahead of a 2016 release date. In that 2015 interview, Reynolds didn't mince his words about the effect the leak had. When asked what moved the needle at the studio, he said: "Exclusively the leaked test footage, 100 percent."

Read more: Ryan Reynolds had to 'let go' of the idea of being paid a huge amount for Deadpool (BANG Showbiz)

It wasn't totally plain sailing from them on though. With a unique character and an R-rating on the cards, Fox slashed the budget to minimise their risk. There was also the risk that pop culture jokes would go out of date during production, though this was partially solved by the use of CGI for Deadpool's mask. Due to this approach, Reynolds had the freedom to record new lines fairly late in the process, keeping everything bang up to date.

When the time came to market the film, Reynolds went into overdrive and harnessed his irreverent social media persona to fire up a campaign with a lot less money to spend than the average superhero outing. Thanks to a star who was willing to go the extra mile, the campaign became an online sensation.

Read more: Vinnie Jones turned down return as Juggernaut in Deadpool & Wolverine (Yahoo Entertainment)

Deadpool went on to make a massive $783m (£606m) at the worldwide box office, which is why we've since had Deadpool 2 and we're within a week of Deadpool and Wolverine. The character is now a pop cultural synonym for any sort of breaking of the fourth wall.

But now, the hero faces his biggest challenge yet. Can the filthy, acerbic Deadpool survive within the confines of the MCU? Well, thanks to two minutes of leaked footage a decade ago, we're about to find out.

Deadpool & Wolverine is in UK cinemas from 25 July.