Oh, the box office. If you're a movie fan, then you've undoubtedly spent way too much time looking up box office grosses. It's a measure of a film's success, and it's a way to see performers who have had their string of misses, as well as their greatest achievements.

There are as number of films that have made a fortune at the box office, but those films aren't always as profitable as some would think. Many movies make their studios a ton of money, but at the end of the day, only one film in cinema history can be considered the most-profitable movie of all time.

Let's see which classic still holds that title!

Box Office Is Anchored By Winners

People have long been fascinated with box office numbers, and films make headlines regularly for their box office performance. Sure, there are countless stories about failed projects, but the box office history is anchored by winners.

To date, there have been 5 movies to crack the $2 billion mark, something that people once saw as an impossibility. Remarkably, a single director is responsible for two of those films, but we'll get back to him later on.

So far, there are 50 films to break $1 billion globally. That's a whole lot of movies that have made a whole lot of cash.

Now that theaters are largely up and running again, and with a heavy slate of franchise offerings for the foreseeable future, it won't be long before the box office sees another $1 billion picture. This film will simply be added to the list, and it will help tell the story of Hollywood's ability to make a fortune.

While there are some truly outstanding films that have made their fair share of coin at the box office, only one film can be called the highest-grossing movie of all time.

Related: Before All The Controversy, Ezra Miller Starred In These Huge Box Office Hits

'Avatar' Is The Highest-Grossing Movie Ever, Sort Of

Remember that director we told you about who had two of the highest-grossing movies ever? Yeah, that'd be James Cameron, who is the man behind the biggest movie to hit the box office.

At the time of this writing, 2009's Avatar is the highest-grossing movie that has ever been released. It was toppled for some time by Avengers: Endgame, but a re-release saw James Cameron's sci-fi flick peak at the top spot yet again.

Though the story has been criticized, Avatar is a force of a brand, and the film still maintains a massive fan base. This is the fan base that was instrumental in getting the trailer for the film's upcoming sequel trending in no time at all.

Avatar is the kingpin at first blush, but its box office gross doesn't tell the full story. When inflation gets involved, the film is suddenly bumped from its top spot. By whom, you ask? That would be Gone With the Wind, a film that brought in over $3.7 billion when adjusted for inflation.

Don't feel too bad for James Cameron, though. Avatar is in second place with over $3.2 billion, while his Titanic is in third place.

Avatar's box office gross is unmatched (sans inflation), but unbelievably, the film is not the most profitable movie ever made.

Related: Before Titanic Leonardo DiCaprio Appeared In A Film That Made Less Than $500,000 At The Box Office

'Gone With The Wind' Is The Most Profitable Movie Ever

So, which film lives on as the most profitable in cinema history? Incredibly, Gone With the Wind is the most profitable film ever made.

"In 2014, the Guinness Book of World Records concluded that the movie had made an inflation-adjusted $3.44 billion; today that would be $3.75 billion and it’s probably a conservative figure. Since “P&A” (prints and advertising) costs in the 1930s were a fraction of what they are today — there was no need to buy ultra-expensive TV commercials, for instance, and far fewer prints were struck — and since MGM kept most of the income from theaters (because it owned so many of them), analysts estimate the movie’s theatrical profit at anywhere from $2 billion up. That number is also an extremely conservative estimate," The Hollywood Reporter said.

The article also mentions that, when adjusted for inflation, the film's budget was just north of $78 million. That's not a ton, and it's low advertising costs and massive box office receipts propelled it to the top spot.

Other highly-profitable movies include Titanic, The Blair Witch Project, and Paranormal Activity.

Related: Keanu Reeves’ Favorite Movie Role Made Nowhere Near Matrix Money At The Box Office

Gone With the Wind might be a relic to some modern movie fans, but at the end of the day, no movie has been more profitable than this classic.

Next: How A Box Office Disaster Forced Francis Ford Coppola Into Bankruptcy