If you somehow missed a year's worth of trailers, commercials, and marketing tie-ins, we have some news for you: Iron Man 3, the latest entry in Marvel's popular superhero franchise, hits U.S. theaters today. Filmgoers who have seen the previous Iron Man movies can guess, more or less, what they're in for: Extensive Robert Downey Jr. quips, sinister villains, and the best CGI explosions that money can buy.

And with the arrival of Iron Man 3, the franchise falls into an elite (but quickly growing) club: The superhero threequel, which began 30 years ago with Superman III. Heroes like Spider-Man, Batman, and Superman have proved popular enough to make it all the way to three films of their own — but by the time a superhero hits that magic number, he usually looks a little worse for wear. How does Iron Man 3 stack up against its superheroic predecessors? Here, a comparison:

1. Superman III (1983)

Budget: $39 million
Box-office gross: $59.9 million (Domestic only)
Positive reviews: 24 percent

It may be the first ever superhero threequel, but Superman III has an equally dubious honor: Kick-starting a long trend of disappointing third entries in superhero franchises. When Gene Hackman opted not to return as Lex Luthor, Superman III swapped in Robert Vaughn as a suspiciously similar corporate villain, and leaned heavily on Richard Pryor's campy, toothless supporting performance. No one was fooled; both commercially and critically, Superman III was a major comedown from its predecessor, barely scraping up half of Superman II's gross. However, it took an even worse entry, 1987's Superman IV: The Quest for Peace, to bring the franchise to an end for good.

2. Batman Forever (1995)

Budget: $100 million
Box-office gross: $336.5 million
Positive reviews: 41 percent

Batman Forever exists in the odd space between sequel and reboot. Tim Burton, the director behind Batman and Batman Returns, was replaced by Joel Schumacher over concerns that Batman Returns was too dark and strange for mainstream audiences. (Burton remained on the project as a producer.) Star Michael Keaton left the film shortly after, leaving Val Kilmer to pick up the cape and cowl to square off against The Riddler (Jim Carrey) and Two-Face (Tommy Lee Jones, in his career-worst performance). Critics were generally unimpressed, but the film was a massive hit, outgrossing every film released in 1995 except Toy Story.

3. Blade: Trinity (2004)

Budget: $65 million
Box-office gross: $128.9 million
Positive reviews: 26 percent 

Though some filmgoers probably weren't even aware of Blade's comic book origins, the vampire hunter was actually the first Marvel hero to earn his own trilogy, beating Tony Stark to the punch by nearly a decade. Unfortunately, the third entry in the Blade franchise was also widely regarded as the worst, adding lame supporting turns from Jessica Biel and Ryan Reynolds and some egregious iPod product placement. In the wake of a notably lower box-office gross, the film series was shuttered, though it did pop up again as a short-lived TV series on Spike in 2006. 

4. X-Men: The Last Stand (2006)

Budget: $210 million
Box-office gross: $459.4 million
Positive reviews: 57 percent

For the third X-Men movie, director Bryan Singer, who had shepherded the first two entries in the franchise, handed the reins to Brett Ratner. (More on that in a minute.) Ratner's take fell prey to all the usual threequel traps: Too many heroes, too many villains, too much narrative bloat. Audiences showed up in droves, but reviews were significantly worse than the previous two films, sparking Fox to embark on a course correction, even though X-Men: The Last Stand is actually the highest-grossing film in the franchise. Fox has since shifted focus away from the main series to spin-offs and prequels, including 2009's X-Men Origins: Wolverine and 2011's X-Men: First Class.

5. Superman Returns (2006)

Budget: $270 million
Box-office gross: $391 million
Percentage of positive reviews: 76 percent

Why did Bryan Singer leave the X-Men franchise? To take another crack at a follow-up to Superman II. More than 25 years after Superman II hit theaters, Singer tossed Superman III and IV out of continuity in favor of his own sequel, which picked up where Superman II left off with Brandon Routh in the lead role. But once again, the Superman threequel underperformed; though it certainly fared better with critics and fans than Superman III, it also cost a lot more. Warner Bros. was underwhelmed with the response, resulting in this summer's upcoming Man of Steel, a reboot that ignores all of the previous Superman films. 

6. Spider-Man 3 (2007)

Budget: $258 million
Box-office gross: $890.9 million
Positive reviews: 63 percent

To many comic book fans, Sam Raimi's Spider-Man 3 represents the nadir of the Spider-Man franchise. But despite its abysmal reputation, it's actually the highest-grossing Spider-Man movie ever released by a considerable margin. Though the film fared worse with critics than its two highly acclaimed predecessors, Spider-Man 3 still received generally positive reviews, and a fourth film — which would reportedly have featured John Malkovich as The Vulture and Anne Hathaway as the Black Cat — was in the early stages of development. But disputes between Raimi and Sony about the future of the franchise marked the end of the first Spider-Man series, which was rebooted as The Amazing Spider-Man in 2012.

7. The Dark Knight Rises (2012)

Budget: $250 million
Box-office gross: $1.08 billion
Positive reviews: 87 percent

The end of Christopher Nolan's Dark Knight trilogy was arguably the most anticipated superhero threequel of all time. Christian Bale put on the mask for a third (and presumably final) time, facing off against Tom Hardy's Bane. It even gave Anne Hathaway her long-awaited chance to star in a superhero threequel as an antihero with "Cat" in her name. Though it lost 2012's superhero box-office crown to The Avengers — and failed to outgross its predecessor — from both a critical and commercial perspective, The Dark Knight Rises is currently the best superhero threequel of all time.

8. Iron Man 3 (2013)

Budget: $200 million
Box-office gross: $307.7 million (and counting)
Positive reviews: 77 percent 

Can Iron Man 3 surpass The Dark Knight Rises to become the biggest superhero threequel of all time? Unlike the rest of the movies on this list, Shane Black's Iron Man 3 hasn't yet had its full day in the sun — but it's off to a pretty impressive start. The film has already earned back well over its budget on international grosses alone, and its 77 percent positive-review mark is higher than Iron Man 2's 73 percent, which makes Iron Man 3 the first superhero threequel to out-review its predecessor.

So there you have it: From both a critical and box-office perspective, Iron Man 3 is currently on track to be the second-best superhero threequel of all time. It's science.