History Main / ThirdActStupidity

* ''Manga/DeathNote'': Light starts out being CrazyPrepared and doing everything possible to preserve his secret, but as he starts buying into his own [[AGodAmI hype]], he starts viewing himself as invincible and stops being so careful. After the TimeSkip, he's gone from [[MemoryGambit erasing his own memory, trusting in the brilliance of his planning to ensure]] [[spoiler:L's death]] [[MemoryGambit while cementing his own complete innocence]]... to ''hiding the Death Note in storage and really hoping no one finds it while he's not looking.''

** The Namek Saga is notable for the guerilla-style tactics that the heroes are required to use throughout: Krillin and Gohan are no match for most of Frieza's elite henchmen, Vegeta is slightly higher up the power scale and ascends higher but is still forced to play it smart to outwit the godlike Frieza. By the end of the saga, Vegeta throws all this careful planning aside and stupidly goads Frieza into transforming, arrogantly believing that Frieza wouldn't get that much stronger; it costs him his life. Not that he had much choice at that point, since Frieza had cornered them and was going to kill everyone regardless, but goading Frieza into transforming faster instead of trying to delay him until Goku could get there to help wasn't exactly a smart move.
** Throughout the Cell Saga, Cell is TheChessmaster and a NoNonsenseNemesis who runs circles around the Z-Fighters and repeatedly outsmarts them since, as he's created from their DNA, he knows how they operate and think; he even manages to achieve his goal of attaining his Perfect form by exploiting Vegeta's ego and [[BloodKnight desire for a challenging fight]] to get Vegeta to help him do so. But after defeating both Vegeta and Trunks in his Perfect form, he lets his ego and pride overcome his common sense, setting up a fighting tournament just to test his skills and giving the Z-Fighters ten days to prepare and grow stronger just so he can have more fun fighting them. However, this is somewhat understandable given the nature of the character. What ''really'' cements him as this is when he discovers Gohan's [[PsychoactivePowers hidden power]] and does everything he can to piss Gohan off so he can unleash said hidden power and receive a real challenge, just as [[BatmanGambit Goku intended]]. Keep in mind that this is the ''exact same trick'' Cell used on Vegeta to get him to help Cell absorb Android 18, and then mocked him to his face for being so stupid as to go for it. Later, in his frustration, he does the exact same thing he mocked ''Trunks'' for earlier: [[HulkingOut buffing up his muscles to crush his opponent with raw power]], [[MightyGlacier at the expense of his speed]], meaning he's now completely unable to land any hits on his opponent and gets defeated that much faster as a result. Cell's forced to resort to a SuicidalCosmicTemperTantrum just to try and [[BetterToDieThanBeKilled force a draw]], and he [[AchievementsInIgnorance had no idea]] that he has the power to return FromASingleCell and CameBackStrong when Goku manages to prevent that [[HeroicSacrifice at the cost of his own life]].

** Hugo Strange in ''VideoGame/BatmanArkhamCity''. He spends most of the game and the prequel comics matching wits with Batman, who has a lot of trouble genuinely messing with his plans because Strange has studied him so thoroughly. In the last third of the game, [[spoiler:Strange takes a hostage over a video screen, forcing Batman to stay still while he lectures him and his goons fill the room. Instead of forcing Batman to not fight back for the sake of the hostage, Strange just lets him go, allowing Batman to knock out all of his men. And despite how familiar he is with Batman's tactics, when Batman begins climbing the tower to his control room and his thugs can't locate him, Strange just assumes he's fallen off.]] Arguably, his lackluster security and decision to control the prison with [=WayneTech=] equipment and having his headquaters on a tower without emergency exits extend to a larger timespan that the third act, but his actions near the climax are more notable.
*** Not to mention the fact that Strange reveals in the ''opening cutscene'' that he knows that Bruce Wayne is Batman, but fails to use this as a way to stop Batman's advance. That he doesn't do it at ''any'' time is bad enough, but it's especially JustForFun/{{egregious}} in the climax, considering it's one of the few times Batman is taking direct action against Strange's plan, rather than dealing with a peripheral issue.

* A FailureIsTheOnlyOption example takes place in just about every Generation in ''Anime/{{Pokemon}}'' with Ash. He will defeat all the Gym Leaders (or befriend them, or [[DefeatMeansFriendship both]]), gain all of the badges, defeat Team Rocket whenever they show up, dismantle the resident criminal organization (unless it's Team Rocket itself, but he will still put a stop to the Team's current plan), save the world and beat a few OlympusMons. But once he gets to the League, unless it's not canon to the games (like the Orange Island League), he will ''ALWAYS LOSE!'' And after that, he will promptly go back home, leave all his Pokémon at Professor Oak's lab except for Pikachu, go to another region and repeat the process from the beginning.
** The Sun and Moon arc of the anime ''finally'' averted this trope after 22 years and seven regions -- Ash wins the Alola League! Hilariously, he's actually stunned for a brief moment before it finally catches up with him.

* ''VideoGame/KnightEternal'': If Dylan [[spoiler:inspected the corpse in the southern cell in Zamaste's castle more closely, he would have realized that the corpse isn't Uno and he could have convinced Stray to stand down without a fight]].

** Throughout the Cell Saga, Cell is TheChessmaster and a NoNonsenseNemesis who runs circles around the Z-Fighters and repeatedly outsmarts them since, as he's created from their DNA, he knows how they operate and think; he even manages to achieve his goal of attaining his Perfect form by exploiting Vegeta's ego and [[BloodKnight desire for a challenging fight]] to get Vegeta to help him do so. But after defeating both Vegeta and Trunks in his Perfect form, he lets his ego and pride overcome his common sense, setting up a fighting tournament just to test his skills and giving the Z-Fighters ten days to prepare and grow stronger just so he can have more fun fighting them. However, this is somewhat understandable given the nature of the character. What ''really'' cements him as this is when he discovers Gohan's [[PsychoactivePowers hidden power]] and does everything he can to piss Gohan off so he can unleash said hidden power and receive a real challenge, just as [[BatmanGambit Goku intended]]; keep in mind that this is the ''exact same trick'' Cell used on Vegeta to get him to help Cell absorb Android 18, and then mocked him to his face for being so stupid as to go for it. Later, in his frustration, he does the exact same thing he mocked ''Trunks'' for earlier: [[HulkingOut buffing up his muscles to crush his opponent with raw power]], [[MightyGlacier at the expense of his speed]], meaning he's now completely unable to land any hits on his opponent and gets defeated that much faster as a result. Cell's forced to resort to a SuicidalCosmicTemperTantrum just to try and [[BetterToDieThanBeKilled force a draw]], and he [[AchievementsInIgnorance had no idea]] that he has the power to return FromASingleCell and CameBackStrong when Goku manages to prevent that [[HeroicSacrifice at the cost of his own life]].

* ''Film/OnceUponATimeInMexico'': The FemmeFatale spots her ex-boyfriend wounded in the street from a distance; the sensible thing to do would be to snipe him, as she was perfectly capable. But instead she goes down to talk to him, so that they could have a dramatic final exchange and [[spoiler: so that Sands could shoot her]].
* None of the characters in ''Film/HellboyIITheGoldenArmy'' make intelligent decisions in the third act, leading to [[spoiler: the villain getting the MacGuffin and the LoveInterest dying]] (although critics felt it didn't hurt the overall film).

* This ends up getting PlayedForDrama in ''Film/AvengersInfinityWar'' courtesy of Thor. Thanos, having spent the entire movie searching for the Infinity Stones, finally gets his hands on all of them. He's prepared to cull half the universe until Thor drives Stormbreaker right into his chest, driven fully by vengeance over the slaughter of his people... and it's during those few moments that [[spoiler: Thanos snaps his fingers.]]
-->'''Thanos''': You should have [[spoiler: gone for the head...]]

* ''[[Literature/GentlemanBastard The Lies Of Locke Lamora]]'' has a case of this when Locke and Jean take on [[spoiler: the Falconer, who can use magic to control people whose true name he knows. The Falconer realizes that "Lamora" is a fake name, but it never occurs to him that "Locke" is also assumed, which of course it is. Without any part of Locke's true name, the Falconer's spell fails, allowing Lock to overpower him]].

* ''Literature/{{Congo}}'': At the beginning, the reader is told about Karen Ross's psych profile, specifically that when she's on the verge of success she gets overconfident and makes stupid decisions. Sure enough, at the end, [[spoiler: she sets off explosive charges to survey the lost city that lead to a volcanic eruption and destroy everything.]]

** Hugo Strange in ''VideoGame/BatmanArkhamCity''. He spends most of the game and the prequel comics matching wits with Batman, who has a lot of trouble genuinely messing with his plans because Strange has studied him so thoroughly. In the last third of the game, [[spoiler: Strange takes a hostage over a video screen, forcing Batman to stay still while he lectures him and his goons fill the room. Instead of forcing Batman to not fight back for the sake of the hostage, Strange just lets him go, allowing Batman to knock out all of his men. And despite how familiar he is with Batman's tactics, when Batman begins climbing the tower to his control room and his thugs can't locate him, Strange just assumes he's fallen off.]] Arguably, his lackluster security and decision to control the prison with [=WayneTech=] equipment and having his headquaters on a tower without emergency exits extend to a larger timespan that the third act, but his actions near the climax are more notable.

* [[http://en.wikipedia.org/wiki/Siege_of_Syracuse_(213%E2%80%93212_BC) The Siege of Syracuse during the Second Punic War]]. To defend his city, Archimedes had designed defensive weapons such as ship-sinking cranes, ballistae, onagers, and possibly even a ''heat ray'' made of focused mirrors. They were so successful that eventually the defenders became overconfident and got drunk on duty, during a festival of Artemis, allowing a group of Romans to breach their defenses and take control of the outer walls.

** Throughout the Cell Saga, Cell is TheChessmaster and a NoNonsenseNemesis who runs circles around the Z-Fighters and repeatedly outsmarts them since, as he's created from their DNA, he knows how they operate and think; he even manages to achieve his goal of attaining his Perfect form by exploiting Vegeta's ego and [[BloodKnight desire for a challenging fight]] to get Vegeta to help him do so. But after defeating both Vegeta and Trunks in his Perfect form, he lets his ego and pride overcome his common sense, setting up a fighting tournament just to test his skills and giving the Z-Fighters ten days to prepare and grow stronger just so he can have more fun fighting them. However, this is somewhat understandable given the nature of the character. What ''really'' cements him as this is when he discovers Gohan's [[PsychoactivePowers hidden power]] and does everything he can to piss Gohan off so he can unleash said hidden power and receive a real challenge, just as [[BatmanGambit Goku intended]]; keep in mind that this is the ''exact same trick'' Cell used on Vegeta to get him to help Cell absorb Android 18, and then mocked him to his face for being so stupid as to go for it. Later, in his frustration, he does the exact same thing he mocked ''Trunks'' for earlier: [[HulkingOut buffing up his muscles to crush his opponent with raw power]], [[MightyGlacier at the expense of his speed]], meaning he's now completely unable to land any hits on his opponent and gets defeated that much faster as a result.

** It wasn't the taunt in of itself that was Zuko's mistake. He taunted Azula for the specific purpose of drawing out her lightning attack. You can even see Zuko preparing to redirect the lightning. Zuko's mistake (aside from just wanting to show off that he had one technique that Azula didn't) was that he underestimated how lucid Azula still was. Even in her VillainousBreakdown, she still thought clearly enough to realize that targeting Katara, not Zuko, was the best move.

** The Monks trilogy of Series 10 technically has Third ''Episode'' Stupidity. [[Recap/DoctorWhoS36E6Extremis "Extremis"]] establishes them as all-seeing, RealityWarper villains planning for every possible contingency in their plan to conquer Earth, which pays off for them in [[Recap/DoctorWhoS36E7ThePyramidAtTheEndOfTheWorld "The Pyramid at the End of the World"]]. They show up at a point where humanity is doomed to be wiped out — unless they give up their freedom to the Monks — '''and''' the Doctor is in a vulnerable state due to [[spoiler:blindness that he won't admit to others]]. The Doctor stops the crisis '''but''' ends up endangered, [[spoiler:and his companion Bill sells out humanity to save him in hopes he can save the day again]]! With that, [[Recap/DoctorWhoS36E8TheLieOfTheLand "The Lie of the Land"]] picks up six months later with the Monks having brainwashed most of humanity into believing them to have always been benevolent superiors. But despite their amazing powers they manage to miss [[spoiler:the Doctor's faked loyalty to them, his companion-assisted escape, and the resultant plan to undo them]] and put up ''very'' little of a fight against the good guys, with only a few tertiary characters perishing. Once their hold over humanity is broken, they... leave. The episode works to justify this by having a character who's previously dealt with the Monks explain that they don't think through ''holding on'' to their power once they have it, but that still comes after two episodes in which they were nigh-omnipotent and the Doctor legitimately had no hope of outwitting them.

* Early in ''Film/SawI'', Adam tries to get a tape recorder that's far out of reach, to which Lawrence suggests using his shirt to snag it, with successful results. When the climax begins, Lawrence is trying to reach a phone just inches away so he can contact his wife; he takes off his shirt and uses it as a torniquet [[spoiler:while he saws off his shackled foot to free himself]]. Apparently, both characters completely forgot Lawrence's earlier suggestion by this point.
* This ends up getting PlayedForDrama in ''Film/AvengersInfinityWar'' courtesy of Thor. Thanos, having spent the entire movie searching for the Infinity Stones, finally gets his hands on all of them. He's prepared to cull half the universe until Thor drives Stormbreaker right into his chest, driven fully by vengeance over the slaughter of his people...and it's with those few moments that [[spoiler: Thanos snaps his fingers.]]

* None of the characters in ''Film/HellboyIITheGoldenArmy'' make intelligent decisions in the third act, which lead to [[spoiler: the villain getting the MacGuffin and the LoveInterest dying]] (although critics felt it didn't hurt the overall film).