"Oh, you're my unlikely hero,I tried so hard but you won't surrender."
—Unlikely Hero, by The Hoosiers.
What would happen if you replaced a Mary Sue with a well-written Ridiculously Average Guy without changing the plot? This trope is a character who gets involved in all sorts of craziness in defiance of all reasonable logic. Basically, they can't even take a vacation without becoming The Chosen One or saving the world. Whereas to a Mary Sue, it's all in a day's work, this character often finds all the craziness surrounding them annoying and must rely on the remainder of the cast to keep their life from becoming an even worse disaster than it already is.
Often, the character has little interest in ever becoming a hero and is basically happy being a Ridiculously Average Guy as long as they get a better job / win the contest / get a date with the hottie / etc. Typically, the character is either a Kid Hero who would rather play video games, or a Deadpan Snarker who has become slightly jaded and Genre Savvy after saving the world 12 times last year. Often Played for Laughs.
- Ash Ketchum from Pokémon. He has come back from the dead thrice, been The Chosen One of countless legends, is one of the few that can manipulate aura, saved the world countless times, and has helped more people then you could possibly imagine. There's like maybe three people outside of his friends who respect him in some fashion.
- Kyon from The Melancholy of Haruhi Suzumiya. Justified by a series of cosmic events so ridiculous it's pretty much a parody of the stereotypical Chosen One. And by "ridiculous cosmic events" I mean God wants to get in his pants, or if you take ire to WMG he IS God.
- Tsugumi Ohba and Takeshi Obata's new series, Bakuman｡ has the two main characters being told that the problem with their manga is the utter lack of special main heroes, and that their series' tend to suffer from average people as heroes.
- All Doraemon The Movie have the Five-Man Band (Or just Nobita) doing something just to justify their want with Doraemon's gadgets. Thus making them end up having to save the world or Plot Device creatures for countless time.
- Most of the Sin City heroes are often on the lower rungs of society and try to live normal lives. They just keep getting wrapped up in the craziness of the city against their wills.
- Rick Jones from Marvel Comics has elements of this. He is more of an Unlikely Sidekick, though. He's just a normal guy who has ended up being the sidekick to a number of heroes from The Hulk to Captain America (comics), usually because he stumbled onto the wrong place at the wrong time.
- Scott Pilgrim. The fact that he was played by Michael Cera in the movie doesn't help either
- Joe in Joe Versus the Volcano.
- In The Relic movie, Margo's just a scientist... who manages to kill the monster (in the book, Marty Stu [but a likable one] Penderghast kills it unspectacularly).
- Another example: Detroit Rock City has four pseudo-stoner losers spend the first half getting into trouble, then the second half just getting the favor of God itself as they luck out on everything.
- Ash in the original Evil Dead film is all over this trope. He works in the hardware department of S-Mart and is just a regular guy. By the end of the film, he's in near-hysterics and is covered in mud, blood, and his own excrement. Of course, in the sequels, this changes dramatically.
- Lionel in "Braindead"/"Dead Alive" is a great example of this trope. He starts out the movie as a timid man living with his mother, and ends up dispatching all the zombies with a lawnmower.
- Carl Frederickson and Russel from Pixar's Up. Just try explaining them someone who's never seen the film. One's an elderly septuagenarian, the other is an overly enthusiastic boy scout who's never been to the wild, and together they fight evil in Venezuela.
- Mind you, hitching your house to a thousand balloons and flying off on an adventure was asking for something to happen.
- Now that this troper thinks about it, pretty much every Pixar character embodies this trope (with a few very notable exceptions).
- Shaun (Of The Dead). He never wanted to be a hero saying his loved ones from the Zombie Apocalypse, he just seemed to be the one could could deal with it pragmatically.
- Joe from Idiocracy. As is stated, he is average in every way.
- Rincewind in Discworld is basically this. All he wants is to be bored and eat potatoes, and all he has to help him is some narrative savvy, a knack for languages and running away, and The Luggage. But he's basically been chosen as the hero of the Disc.
- Tavi in Codex Alera. The whole series started because he was looking for some lost sheep, though eventually it becomes apparent that he was actually the heir apparent to the entirety of Alera.
- Bilbo Baggins. Possibly the ur-example.
- His nephew Frodo, to a lesser extent.
- The title character of Farmer Giles of Ham.
- Richard of the Sword of Truth considers himself this for the first book and part of the second. He finally accepts his powers and heritage, and the responsibilities that come with them.
- Gordon Freeman of Half Life. Just an average everyday theoretical physicist until that fateful day, he ended up fighting off hordes of aliens while beating back those pesky black ops trying to keep him quiet, then goes into the other dimension to fight the creatures on their own turf, culminating in defeating their all-powerful overlord to prevent the entire earth from being invaded by the things. And all this with a magical satchel of fairly common weaponry with the occasional science fiction import.
- U-1 is a really unlikely hero. Basically, he came back to his house after getting beaten up, which prompts his dog to teach him how to Gitaroo. Right after, a demon with an axe threatens to chop U-1 in half, and the next thing you know, he's actually from a bloodline that automatically makes him the Chosen One for a faraway planet. I don't get it either, just go with it.
- Super Smash Bros Ultimate Adventure Mode starts with every member of the main cast vaporized and replaced by evil doppelgangers, courtesy of the Big Bad; all but one... little Kirby. He has to be the one to find and rescue the Spirits of the others, so they can defeat the villains and save the day, so to speak.
- Droopy, in about half the Tex Avery shorts in which he appears, plays the Designated Hero to Red, who's often victimized by Wolfie, Butch or Spike. Then they wind up pissing Droopy off...
- Fry in Futurama.
- Coop in Megas XLR is just a fat slacker who obsessively plays video games and works on his automotive craftsmanship. He also happened to stumble upon the titular Humongous Mecha at a junkyard and got it for a steal, modifying it to work with his car. All the while, he remained oblivious about its importance until he finds himself face to face with a girl from the future and is reluctantly chosen to be the hero because only he can pilot it at that point. From there, he mostly regards this role as secondary to eating and playing video games.
- Well, at this point, he should be in his friggin' twenties...