Science Fiction (Sci-Fi) films generally cost a lot of money - unsurprising when you consider they often rely on special effects, sometimes at the expense of acting, talent and plot. Trying to make a budget sci-fi film is a lesson in futility; you aren't going to break box office records if people can see the wire holding up the spacecraft or you simply paint your aliens a different color to the normal selection found on the human being's natural palette.
To make this list, certain criteria had to be adhered to. Firstly, the box-office gross has not been adjusted for inflation. Everyone knows Gone with the Wind is the box-office champion of all time when its $400 million from 1939 is taken into account by today's inflated standards (although there aren't many marauding dinosaurs or hostile aliens in that one). Secondly, the list has been ordered by worldwide gross, not just domestic gross. Thirdly, and perhaps most controversially, there are no superhero films in this list - we've saved that sub-genre for another day - which means no The Avengers holding up second spot. Considering aliens and spacecraft are abundant in this blockbuster, it may seem odd not to include it, but the superhero niche is more of a standalone in the science fiction world. Star Trek fans may also want to look away now, as the highest-grossing Trek film is Star Trek: Into Darkness, which made $467 million worldwide and is only 138th in the all-time list (at the time of writing), just behind The Hangover.
10 E.T.: The Extra-Terrestrial: $792.9 million
Just pushing out the classic that is Star Wars (1977) and the Indiana Jones and the Kingdom of the Crystal Skull (2008) is this 1982 effort from Steven Spielberg. Featuring a cuter alien than those found in fellow 1980s classic Aliens, this one sports a magic finger and does not drip acid all over the carpet. ET featured an adorable young Drew Barrymore, before child stardom went to her head and she went a bit crazy for over a decade.
9 Independence Day: $817.4 million
There was a time when mixing Will Smith with aliens was box-office gold (until 2013's After Earth). This was the case in 1996, when Independence Day set global box offices alight. It wasn't a cheap film to make, costing $75 million (ET cost a puny $10.5 million in comparison). It was gung-ho, dripping with silly dialogue and as deep as an alien's pockets (they never seem to wear trousers). But the special effects were outstanding - and if nothing else, the movie's success was testament to the fact that people love seeing important buildings getting blown up in films.
8 Inception: $825.5 million
OK, so this one does not contain any aliens, monsters, spaceships or Death Stars, but it's certainly confusing enough to be a sci-fi film. The fact that Leonardo DiCaprio and his team of dream infiltrators are using "military technology" (i.e. a "MacGuffin") to carry out their nefarious business means this 2010 Christopher Nolan film earns its place in the noble realm of science fiction. The film cost $160 million but made a killing at the box office, with people attending multiple times just to decide whether (spoiler alert!) the protagonist, Cobb, is dreaming at the end or not.
7 Transformers: Revenge of the Fallen: $836.3 million
This 2009 Michael Bay film is deeply unloved. The critics hated it - 'interminable' and 'painful... overproduced action' were among the slights - and many cinema-goers felt they had just experienced nothing more than a cerebral overdose of giant robots. It wasn't great filmmaking, but this incredibly expensive, action-packed movie ($200 million plus) made a huge amount of money at the multiplexes. Bay's two other attempts at bringing Autobots and Decepticons to life were slightly less brain-damaging than this effort - at least according to critics. A 4th movie is set for release this year, though, so watch this space.
6 Star Wars Episode III: Revenge of the Sith: $848.8 million
Another "Revenge" film in the list, sci-fi is always ripe for a bit of revenge - such is the nature of the genre. Star Wars films always manage great box-office scores, being such a beloved series as it is. George Lucas may have disappointed fans with the first film in his prequel trilogy, but the third offering in 2005 had less Jar Jar Binks, fewer "cute" kids saying "oops" (surely even as a child Darth Vader would never say "oops"?) and more Sith evil than its two predecessors, making it the biggest critical hit of the prequels.
5 The Hunger Games: Catching Fire: $861.3 million
It seems that the whole word is in love with Katniss Everdeen and Peeta Mellark at the moment. This 2013 film which, at the time of writing, was still in some theaters around the world, has built upon the success of the first film in the series, which made a very respectable $691 million itself. With The Hunger Games: Mockingjay - Part 1 and Part 2 to come, in 2014 and 2015 respectively, expect to see one or both of these films hitting the heady heights of Harry Potter territory when it comes to gargantuan box office gross. This series was instrumental in making Jennifer Lawrence a huge star, and a pop culture icon.
4 Star Wars Episode I: The Phantom Menace: $1,027 million
Star Wars fans had waited years for this 1999 space opera epic. It was going to be brilliant, life-changing, a piece of genius that would captivate a whole new generation of Star Wars fans. Well, no, not quite. The visual effects were good, Darth Maul was an interesting villain and Liam Neeson was professional as Qui-Gon Jinn. But it was just impossible for the film to satisfy all the hype, although it did become the 14th highest-grossing film of all time (of all genres). So fans might not like how Lucas wrote it, but he can always stuff his ears full of dollar bills to avoid listening to their complaints.
3 Jurassic Park: $1,029 million
A relative golden oldie compared to the rest of the sci-fi blockbusters in the top half of this list, this 1993 dinosaur movie was incredibly successful, raking in over a billion dollars from a $63 million budget. Steven Spielberg's classic astounded audiences worldwide, especially with the initial special effects introduction of a giant Brachiosaurus going about its business. The film won three Oscars in 1994 and helped cement Spielberg's position as one of the premier sci-fi directors of his generation.
2 Transformers: Dark of the Moon: $1.123 billion
Ranking sixth in the all-time list of highest-grossing films, beating out efforts from the Pirates of the Caribbean, The Lord of the Rings and Batman, is the third outing for Michael Bay with the Transformers franchise. This 2011 film was grittier than its disappointing prequel but was still an example of "trash cinema," to be used once and then forgotten; however inexplicable, this is still one of the most successful films of the modern age, according to the profits.
1 Avatar: $2.782 billion
The 2009 James Cameron film that is not only the highest-grossing sci-fi film, but is also the highest-grossing film of all time (when not adjusted for inflation). With over $2.7 billion grossed, Cameron was indeed the king of the world considering the film cost $237 million to make and $150 million to promote. That's still a profit of well over $2 billion. The maverick director made his 3D adventure a must-see event; regardless of the fact that stripped of its effects Avatar has a storyline so thin that you could sneeze a hole through it. Cameron is now busy in New Zealand making Avatar 2...and Avatar 3...and Avatar 4!