5. The Wolverine (2013)
While it may not have seemed possible when the first X-Men movie was released, Hugh Jackman's 'Wolverine' has risen to become one of the most successful, beloved, and recognizable superheroes in the modern age of comic book blockbusters. So fans were elated when director James Mangold promised that his crack at the mythology - The Wolverine - would be taking the character more seriously than his previous solo outing, setting almost the entire film in Japan. And for most of the film, the story and themes fit perfectly.
Then came the third act. Where Wolverine had been forced on a journey of introspection, rebirth, renewal, and a brush with mortality, the climax of the film saw him fighting an enormous Adamantium samurai and a venomous mutant femme fatale. While the preceding film worked on drama and urban martial arts action, the film's final fight descended into the far-fetched comic book realm that Fox had promised to be stepping out of. Luckily, Days of Future Past proved that Logan doesn't need to fight to be interesting, but The Wolverine remains a story that Jackman (unintentionally) described perfectly: two movies in one. And one of them was long overdue.
4. High Tension (2003)
Horror movie fans are a fast-learning bunch, with modern audiences attempting to identify a slasher movie's killer from the very first scene. Is it the best friend? The lovable loser? The main character themselves? Or a band of cannibal hill people? Understandably, horror filmmakers have come to rely on twist endings as a final thrill, as fans have come to expect them just as reliably. Such is the case with French indie slasher High Tension, depicting a weekend retreat gone horribly, horribly wrong.
Unfortunately, the film's twist ending - the depraved killer is a split personality of the main character - spoils the experience. The twist itself is nothing new for the genre, but the reason why it's so shocking in High Tension's context is that it simply doesn't make sense. After a moment's thought, entire sequences seem implausible the way they have been presented, if not completely impossible. It's a shocking twist, but for reason that left viewers annoyed, not enlightened.
3. I Am Legend (2007)
There's no shortage of criticism when it comes to adaptations of Richard Matheson's novel "I Am Legend," yet I Am Legend keeps surprisingly close to the novel for much of the story, following Robert Neville (Will Smith) as he attempts to find a cure for a disease that has ravaged almost all of Earth's population. But as he traps, tests, and kills specimens on a daily basis, events hint that his view of the afflicted as 'mindless animals' is not necessarily correct. The mysterious monsters begin to set elaborate traps, with one enduring pain in order to show concern (or send a message?) for a captured female.
When the film comes to a head, Neville (and the filmmakers) ignore the evidence altogether, handing a 'cure' to other survivors, and blowing everyone up with a hand grenade. It was an odd ending given the build-up, so audiences weren't surprised when the film's alternate ending came to light, in which Neville realizes he has killed countless thinking, feeling people, returns the test subject to her loved ones, and somberly takes his cure to the last surviving humans. The fact that online commenters seemed to almost universally prefer the alternate ending shows that the studio made the wrong call - and the film's conclusion suffers because of it.
2. Sunshine (2007)
Few directors have managed to apply their talents across as broad a spectrum as Danny Boyle. With the likes of The Beach, Trainspotting, 127 Hours and 28 Days Later spanning from horror to survivalist drama, his foray into science fiction was certain to be thought-provoking. And with Sunshine, he delivered - for the most part.
Following a small crew of astronauts charged with re-starting the Sun to save Earth from a solar winter, the film almost immediately began delving into the psychology of space travel, a truly multicultural future, and man's role in the universe. But just as it seemed that the film had earned its place among the likes of 2001: A Space Odyssey, Alien, and Solaris, the film takes a hard right turn, replacing isolation and introspection with a run-of-the-mill slasher movie. Sunshine is still hailed as a success for how much it got right, but its final act remains disappointingly predictable - not to mention out of place.
1. Superman (1978)
We all know that Richard Donner's Superman: The Movie will forever be considered the 'best' film version of the superhero by many. Promising to make audiences believe that a man can fly, the film did just that - which is why its ending was so puzzling. The film's climax saw Lex Luthor's devious plans come to fruition, with Superman forced to choose which American coast to save, resulting in the death of Lois Lane (Margot Kidder).
Enraged, Superman lets out a scream as he takes to the skies, and begins flying around the Earth - against its rotation - as fast as possible. What appears at first to be a tantrum is soon revealed to be much more, as the catastrophe and destruction rewinds, revealing the Kryptonian to gain control over time itself. No matter how you explain it, suddenly granting the hero such power is never explained, despite forever changing the mythology. The film's place in history allows this ending to be overlooked (like the memory-erasing kiss in its sequel), but shows the corner the filmmakers backed themselves into with a story meant to shock, but refusing to commit.
As long as there are underwhelming movies, there will be fumbled third acts that held them back from greatness. But as this list shows, even a movie with themes, story, or characters under-served by poor endings can have its fans, and still stand above films that never even had a chance at their success.
Follow Andrew on Twitter @andrew_dyce.