Avatar opened on Dec. 18, 2009, to a respectable $26.7 million at the box office. That's impressive, but nowhere near the all-time opening day record. Across its first week Avatar ended up bringing in $137 million in domestic box office, just the 28th largest opening week. 

Yet, what was incredible about Avatar was how the film's momentum continued to grow across its run. Most blockbusters lose 50% of their box office gross in the second weekend and continue dwindling each and every week until they leave theaters. 

Avatar lost just 1.8% in its second weekend, its third weekend brought in $68.5 million, a drop of just 11% from its opening weekend. It set the box office record for largest third, fourth, fifth, sixth, and seventh weekends. In multiple weekends, it actually grew from the prior week. It stayed at number one at the box office for a mind-boggling 8 consecutive weeks.

Add it all up, and Avatar ended up breaking the domestic record for largest total box office with a lifetime gross of $761 million. In international markets it brought in more than $2 billion at the box office, bringing its worldwide total to nearly $2.8 billion, another box office record.  

Only one other recent movie had a comparable run -- Titanic stayed at number one at the box office for an astounding 17 consecutive weeks. It's second all-time at the box office with a worldwide lifetime gross just south of $2.2 billion. Adjusted for inflation, Titanic would be closer to $4 billion in global box office.  

Clearly, breaking the box office record won't be easy. Both Avatar and Titanic fall in the "maybe once every decade" cultural sensation category. Each film was "must see" in theaters, and both rode a wave of buzz and word of mouth. 

Yet, records are made to be broken, and Avatar's box office record is no different. Let's take a look at three movies that have an outside shot at beating its record. 

Star Wars: Episode VII

In spite of being widely panned by both audiences and critics, Star Wars: Episode I-The Phantom Menace brought in over a billion in box office receipts across the globe. That figure is even more impressive when you consider the movie came out in 1999, meaning that its adjusted-for-inflation figure would put it around $700 million domestically, in the same ballpark as Avatar

The Phantom Menace's box office haul shows the enduring popularity of Star Wars as a franchise. There is little doubt the prequels tarnished the franchise, but Disney (DIS -1.01%) shelled out more than $4 billion for the rights to the franchise for a reason. 

Part of the huge promise behind the newest franchise is a chance to start over, leaving the prequels behind. Gone is George Lucas and in his place is the hyper-talented director J.J. Abrams. That's especially promising as Abrams has not only resurrected the Star Trek franchise, but was also the executive producer of Lost among many other successful movies and TV shows. 

Add up one of the best directors around working on his dream project with a franchise with near limitless potential, and the odds increase dramatically that the next Star Wars could get the kind of buzz and word of mouth that sends it to a long box office run, which could challenge Avatar. 

The Avengers: Age of Ultron

The Avengers sequel gets a nod over the upcoming Batman vs. Superman as the comic-book-based movie most likely to challenge Avatar. 

Why is The Avengers 2 on the list? First, the first movie did very well, bringing in $623 million domestically and over $1.5 billion globally at the box office. Both those totals best The Dark Knight Rises' box office, which was just shy of $450 million domestically and $1.1 billion globally. The Avengers 2 will also benefit from the continuing popularity of not just the first film, but surrounding Marvel properties. Iron Man 3 brought in more than $1.2 billion this summer, an enormous jump from the $623 million Iron Man 2 brought in across the globe. 

It'll be a challenge besting the first Avengers' huge box office haul, but we have seen comic book movies grow as series progressed -- look no further than the comparison between Iron Man 2 and Iron Man 3 above. Overall, The Avengers: Age of Ultron might have a better shot at the domestic crown, where it finished with about 80% of Avatar's box office. Internationally, it earned less than half of Avatar's total. 

Avatar 2 

It might not be the most original pick among movies that could best the first Avatar's box office record, but it's the most likely. 

Still, even with sequels routinely besting the box office haul of the original film in recent years, Avatar 2 beating the original's box office is far from a slam dunk. One of the key areas of success for Avatar was its inclusion of 3D. It was a film built around its use of gorgeous visuals and ground-breaking 3D landscapes, the spectacle of which brought moviegoers flocking to cineplexes. 

With years of advances in CGI and 3D now expected for major films, Avatar 2 won't feel nearly as unique as the original. Also, the first film felt like a complete story. Movies based around comic books have the advantage of a host of villains that characters can face off against. Sequels rarely feel forced. 

Still, the movie Gravity is proving that well-done 3D films can still be a huge box office draw. It drew a reported 84% of ticket sales from 3D showings this weekend. If the next Avatar can up the ante and receive rave reviews from critics and viewers, it could ride the momentum from the original to big box office results. 

Out of left field

There you have it, three films that could challenge Avatar's box office record. However, keep in mind that few saw Avatar becoming a threat for the box office record before its release. Likewise, Titanic was seen as a potential bust before its release. It faced a grueling production schedule and was the most expensive film ever made at the time. Yet, it more than validated the cost of production and surpassed all expectations. 

The moral of the story? While it's fun to handicap the success of future films, the next box office champion is probably something that has yet to be thought up.