[[quoteright:334:http://static.tvtropes.org/pmwiki/pub/images/Isawthedevil_8170.jpg]]
->''"I will kill you when you are in the most pain. When you're in the most pain and shivering out of fear, then I will kill you. That is a real revenge. A real, complete revenge."''

''I Saw the Devil'' is a 2010 Korean {{Revenge}} movie directed by Kim Ji-Woon (''Film/ATaleOfTwoSisters'', ''Film/TheGoodTheBadTheWeird'', ''Film/ABittersweetLife''). It stars Lee Byung-Hun as Kim Soo-Hyun, a government agent who swears to violently avenge the murder of his fiancée. Said crime was commited by Kyung-Chul Jang (Choi Min-Sik), a psychopath to whom kidnapping, raping and murdering young women come as easy as breathing. What ensues is a dangerous cat-and-mouse game in which both men vow to destroy one another's life.
----
!!This movie provides examples of the following:

* AgonyOfTheFeet: Kyung-Chul's ''both feet''. [[spoiler:One has its Achilles Tendon cut, another steps on a fishing hook]]
* AntiHero: Soo-Hyun, who doesn't seem to care that his plan for revenge also puts innocent bystanders in danger. [[spoiler: At one point he lets Kyung-Chul rape someone long enough just so he could disrupt his enjoyment that much further.]]
* AssholeVictim: The two crooks in the taxi plan to rob and kill Kyung-Chul, who figures it out and kills them both.
* AttemptedRape
* BittersweetEnding: [[spoiler:Soo-Hyun manages to murder Kyung-Chul, but then he realizes [[HeWhoFightsMonsters what he's become.]]]]
* BlackComedy: A good example is when Tae-joo tries to remove the screwdriver pinning his hand on the table. The handle promptly comes off, and he slams the table in frustration, before deciding to lift his hand up along the shank.
* BottomlessMagazines: A mild case when Kyung-Chul shoots three times with a double barrel shotgun before reloading.
* {{Bowdlerized}}: The Korean version was effectively censored by the Korea Media Rating Board; several shots of violence and some scenes depicting cannibalism had to be removed before being released. The international version is uncut and true to the director's intentions, however.
* CowboyCop: Soo-Hyun.
* CurbstompBattle: Kyung-Chul is very skillfully beaten whenever he engages Soo-Hyun in hand-to-hand combat. Justified in that Soo-Hyun is a trained government operative.
* {{Determinator}}: Soo-hyun[[spoiler:, but not as much as Kyung-Chul]]. To elaborate, [[spoiler: Kyung-Chul gets into a car accident and breaks his arm. Later he has the tendons in one of his feet cut. Not long after his head is bashed in with a pipe. Through all of this, he is still somehow able to inflict brutal murder when in any normal situation, he could have been defeated by being shoved to the ground and kicked.]]
* DevilInPlainSight: How Soo-hyun sees Kyung-Chul. The title, which explains it all, is considered an ironic coincidence.
* DisposableWoman: Joo-Yun.
* FilmNoir
* FromBadToWorse
* GlasgowGrin: [[spoiler: Soo-Hyun gives this to one of the cannibals by ripping open his mouth with his bare hands.]] We only see it briefly.
* {{Gorn}}: Oh boy.
* HeWhoFightsMonsters: Explored and discussed.
* HypocriticalHumor: Kyung-Chul often calls everyone crazy and/or psycho.
* IdiotBall: The Police has it bad. They have called Kyung-Chul in before, and know where he lives. So [[spoiler: When Kyung-Chul left all his evidence at the crime scene at the start of the movie, why didn't they get him then?]]
* ImAHumanitarian: Kyung-Chul is friends with some cannibals.
* InfantImmortality: Just about the first thing the film does is subvert this.
* JackBauerInterrogationTechnique: Soo-Hyun uses this on some suspects early on when he's looking for the killer.
* {{Jerkass}}: Aside from the whole SerialKiller business, Kyung-chul treats every last person he comes across with violence, hostility and contempt - and that's when he doesn't end up killing them.
* ManlyTears: At the end, [[spoiler:Soo-Hyun breaks down crying after finally killing Kyung-Chul]].
* MuggingTheMonster: The two crooks in the taxi plan to rob and kill Kyung-Chul, not knowing he is a murderous psychopath.
* NiceJobBreakingItHero: Soo-Hyun's constant catch-and-release torment of Kyung-Chul gives the latter time to find out Soo-Hyun's identity. Kyung-Chul then [[spoiler: tracks down and murders Joo-Yun's father and sister. Had Soo-Hyun finished his revenge earlier, his fiancee's family wouldn't have been killed]].
* NotIfTheyEnjoyedItRationalization: A scene only available in the Korean version of the film (the director cut it out of the international version for pacing reasons) has Kyung-Chul raping his cannibal friend's wife only her for to enjoy it after a while.
* OvertOperative: Soo-Hyun
* ParentalAbandonment: Kyung-Chul has a son whom he left with his parents.
* PayEvilUntoEvil: Soo-Hyun's vow.
--> ''I'll promise this. I'll give him pain that's 1,000 times... no, 10,000 times more painful.''
* [[spoiler:TheKillerBecomesTheKilled]]
* {{Revenge}}:
** RevengeBeforeReason: What eventually defines Soo-Hyun.
* SacrificialLamb: Joo-Yun, whose death at the hands of Kyung-Chul kicks off the plot.
* SerialKiller: Kyung-Chul.
* [[spoiler:SerialKillerKiller]]: Soo-Hyun
* ShoutOut: Kyung-Chul ends up in a situation straight from ''Film/BloodsuckingFreaks'': [[spoiler: in a guillotine, holding the blade up with his teeth]].
* SmallNameBigEgo: Kyung-Chul. Even though he's a sleazy serial killer whose only known "friend" is [[spoiler: a psychotic cannibal]], he thinks very highly of himself. [[spoiler: And doesn't change his tune until the moment he is brutally killed.]]
* SoftGlass: Soo-Hyun knows that this is not true. The only time he jumps through a window, he wears gloves and a rather thick hoodie, and also grabs a sheet of cloth for extra protection.
* TooDumbToLive: Averted. Joo-Yun quickly realizes there's something strange about the man offering to help her with her flat tire, declines his help, and rolls up her windows and locks her doors. [[spoiler: It doesn't save her.]]
* TranquilFury: Soo-Hyun maintains this state throughout the movie.
* UnderestimatingBadassery: Soo-Hyun eventually discovers what a bad idea it is to keep a deranged psychopath alive to toy with.
* VillainousBreakdown: Near the end of the movie [[spoiler:Soo-Hyun succeeds in getting Kyung-Chul to beg for his life like so many of his own victims. Subverted in that it was an act on Kyung-Chul's part]].
** [[spoiler: Then played straight when Soo-hyun leaves and Kyug-Chul's parents and son come to visit him. Kyung-Chul really starts to panic as they're about to see him in the state Soo-hyon left him in, holding a rope with his teeth that, if released, would let the guillotine down]].
* WickedCultured: The Cannibal Tae-joo enjoys listening to classical music while preparing his "meals".
* WhatHappenedToTheMouse: What happened to the schoolgirl and the kidnapped victim in the cannibal's house? Also, [[spoiler: Soo-Hyun's sister-in-law, though {{WordOfGod}} has it that she was killed.]]
----