WARNING: In many cases, the very fact that this trope applies to a work serves as a spoiler. Proceed at your own risk.
Protagonists becoming increasingly villainous in Live-Action TV series.
- 24 as a whole does this for Tony Almeida, Allison Taylor, Renee Walker, and Jack Bauer himself; with Tony's arc following through in season 7 and Taylor, Walker and Jack going through this by the final season. By the time it's over, none of them are that much better than the terrorists, either by willingly aiding them, endangering innocent people to selfishly enact revenge on them rather than mete out any true justice, or both. Though in the case of the latter three they do ultimately see the light by the end. Counting sequel series, the former eventually does as well.
- In Babylon 5 Londo Mollari's arc is basically his descent into this trope and then his struggle back out again.
- Mitchell goes through this throughout the seasons in Being Human he starts off as a genuinely good guy, fighting his addiction. Then after Herrick is temporarily killed off by George, he becomes the leader of the Vampires in Bristol and manages to convince most, if not all of them to let go of their blood addiction...then their gathering place is bombed by a person he trusted. He then crosses the Moral Event Horizon and kills 20 people in a train. Then instead of trying to redeem himself, he sinks further and further into depravity and keeping secrets during Season 3, focusing on trying to save his own life and keep his role in the massacre secret, which concludes with him outright asking his friends to kill him so that he won't become a monster again.
- Boardwalk Empire starts out with Nucky Thompson already long established as a Corrupt Politician and mastermind behind a criminal operation which soon turns to bootlegging when Prohibition legislation is passed. However, much of season 5 focuses on a younger version of Nucky growing up in Atlantic City and his turn to criminality to advance himself by making a Deal with the Devil with the Commodore to contrast with the present day collapse of Nucky's empire.
- Cesare Borgia from The Borgias is a perfect example of this (which makes sense, as he, historically, was the inspiration for Michael Corleone. He starts out as The Dutiful Son, a reluctant priest who would do anything to protect his family. Over the course of two seasons, he grows into the Magnificent Bastard who would inspire Machiavelli's "The Prince"... and murders his brother, thus destroying his relationship with his parents.
- His sister Lucrezia (with whom he shares a good deal of Villainous Incest subtext before they eventually have sex) does this on a lesser scale. She's ultimately a good person but is still quite the manipulative bitch with a mean streak.
- Breaking Bad has arguably become the modern-day codifier, with five seasons made entirely of this. Walter White starts out as a decent, law-abiding and substantially sympathetic character, who clearly loves his wife and children and is driven into a "victimless" crime in order to pay the bills after he's diagnosed with late-stage cancer. However, by the end of the first episode, he has already brought someone near-death, and before the first season is over, he has already turned down legitimate means of business, because his main motivator is his Pride. The show's creator Vince Gilligan said that his goal was to turn Mr. Chips into Scarface.
- From there, he spends four long seasons falling deeper and deeper into villainy. It's explored from every angle, always giving Walter some excuse or justification until the viewer finally notices that Walter is enjoying all of this. He willfully dives back into the criminal world at every opportunity even when given real chances to get out, abuses every connection ruthlessly to get what he wants, and leaves a massive trail of bodies in his wake culminating in the destruction of many innocent lives (inevitable given his meth business), and the ripping apart of his family. Worse is how he drags his partner, Jesse, down with him, first giving the messed up kid a real sense of self-worth, and then systematically taking away so many of the things that he loved.
- By the end of the series, Walt is either directly or indirectly responsible for more deaths than everyone else in the series combined, two characters who hate each other can agree that Walt is figuratively the devil, and everyone in his family, his partner, and most of his business associates, have wanted him dead at some point.
- Similarly, the prequel Better Call Saul chronicles the journey of an ex-con and aspiring and hopeful lawyer Jimmy McGill to the criminal lawyer Saul Goodman, who willingly throws in with criminals like Walt and Mike just to earn some extra money, and is very evident in comparison with Jimmy and Saul in Seasons 1 and 6. In Season 1, Jimmy swore off all connections with the cartel after almost getting killed by Tuco and tried to fight for the elderly being defrauded by their residential company, whereas by Season 6, Saul has used the elderly to just to bump off a potential competitor from the bar association, created a scheme to defraud Howard and HHM just for petty vengeance even when Howard himself was willing to forgive him and bring him to HHM, and tricked the entire jury into releasing the very guilty Lalo Salamanca, enabling him to cause further murders. It takes him nearly murdering an elderly woman to save his own skin for him to realize how far he's fallen from the crusading elder law lawyer he aspired to be.
- On Buffy the Vampire Slayer, Willow gets pushed on the journey to villainy in season 6. though she's already well on her way by mid-season 4 with her continuing attempts to use magic for control over others, the lack of any real consequences for her actions, and the lack of deterrents against her using magic for whatever she wills. Her villainy really culminates with the mind-rape/rape of Tara mid-season 6 and total refusal to acknowledge that what she did was wrong and why. Everything after that (killing Warren, trying to kill Buffy et al.) is just follow-up.
- Cobra Kai: The series is in many ways defined by this trope.
- Inverted by Johnny Lawrence. After being the bully in The Karate Kid (1984), he is the protagonist this time around and is actively trying to better himself by battling alcoholism and teaching bullied kids to stand up for themselves. He is still a drunken, sexist, foul-mouthed Jerkass with his head stuck in the past, but he is definitely working on being a better person.
- Daniel LaRusso, meanwhile, is also stuck in the past, and uses increasingly immoral methods to fight the resurgence of Cobra Kai, since he firmly believes that the modern Cobra Kai is exactly as bad as the one that Terry Silver indoctrinated him into in The Karate Kid Part III, and refuses to believe that Johnny has changed and that John Kreese was the reason Cobra Kai was the haven for bullies it was.
- The series ultimately proves that while Daniel may or may not have been justified, he was right. Johnny's students take to the least savory parts of the Cobra Kai ethos with the zeal of converts, and by the end of the second season, Johnny drinks himself into a stupor when he finds out first-hand just how brutal and ruthless his students are. Though he fails to realize that unlike Kreese, Johnny is mortified at what he's turned his students into and wants to put a stop to it. His failure to recognize that creates a new set of problems.
- In season 1, Johnny's son Robby Keene goes to work for Daniel to spite his father, and despite his original ulterior motive, Robby grows to appreciate Daniel's faith in him and turns against his miscreant friends. Robby becomes Daniel's Miyagi-Do karate student and flourishes under this tutelage, coming in second place to Miguel Diaz in the All-Valley Tournament. In the second season, Robby continues to train under Daniel and begins dating Daniel's daughter Sam. But he's insecure about Miguel's constant efforts to reconnect with Sam, and things come to a head in the season finale when Sam cheats on him with Miguel and Miguel throws this in Robby's face during the school brawl. An enraged Robby kicks Miguel over a railing, leaving him paralyzed while Robby spends season 3 in juvie. Kreese then takes advantage of Robby having fallings out with both Daniel and Johnny to get under his skin, getting Robby to buy into the Cobra Kai mentality. The final straw is when he catches Sam having an intimate moment with Miguel and she steps in to stop Robby from attacking him, prompting Robby to go to Cobra Kai and throw his lot in with Kreese.
- Played with in Doctor Who, especially with Seven and Ten, the most scheming and manipulative of his incarnations. The threat of the Valeyard has hung over everything the Doctor has done since Six, and the Doctor has done some truly horrible things for the sake of what he thinks is right, up to and including genocide (of his own people, albeit only to stop them doing worse to the entire universe), and Big Finish has done a couple of alternate continuity audio dramas of the Doctor gone bad note .
- More specifically, the final stretch of Series 9 ("Face the Raven"/"Heaven Sent"/"Hell Bent") covers the Twelfth Doctor taking this journey when No Good Deed Goes Unpunished for him. A plot to capture him hatched between Ashildr and the Time Lords, people who owe their lives to him, inadvertently leads to not only his capture but the death of his companion Clara. Imprisoned in a gigantic torture chamber after this, alone save for the Monster of the Week and thus without any kind of Morality Chain, he undergoes a Sanity Slippage as he lets his anguish overwhelm him and emerges a Woobie, Destroyer of Worlds who risks the safety of the entire space-time continuum just to get Clara back. In the end, he repents of his understandable but unacceptable behavior and returns to his best self when he has his memories of her wiped relieving him of the anger and grief that drove him to extremes. In fact his overall Myth Arc reverses the journey some Doctors had as he starts out grumpy, secretive, insensitive, and ruthless (it's heavily implied he outright kills his first major opponent, the Half-Face Man, although it's clear he doesn't have other options), but "dies" as one of the kindest, most loving Doctors of all. He even gets his memories of Clara back shortly before regenerating. His last line — "Doctor, I let you go." — is even the inverse of Ten's "I don't want to go."
- Game of Thrones includes this as the final Plot Twist. Where Daenerys Stormborn completes her ascension into the Big Bad right before the finale.
- This trope is the whole point of Hannibal. Hyper-empathetic, anti-social FBI profiler Will Graham is manipulated by Hannibal Lecter into becoming a killer.
- In The Hollow Crown: The Wars of The Roses, Richard of Gloucester (later Richard III) starts as honorable young man fighting for his family's claim to the throne, but the murders of his father and younger brother, the brutality of war, his incompetent older brothers, and the fact that he can never lead a normal life because of his deformities lead him to become a ruthless, backstabbing, cold hearted swordsman who kills his way to the crown, cares for no one and dies alone in the battle of Bosworth.
- This trope serves as the premise of Kamen Rider Zi-O, the Milestone Celebration series for the Heisei era of Kamen Rider. Sougo Tokiwa’s dream is to be the greatest king in history and he succeeds fifty years later...by becoming Oma Zi-O, a demon king responsible for the Bad Future shown in the Cold Opening. Due to Oma Zi-O's strength at that point and time being far too terrifyingly powerful for anyone to challenge directly, multiple factions go back in time to 2018 in order to prevent the rise of the tyrant - for better or for worse. The only question in present time is whether or not Sougo can actually defy his seemingly set path and change the future without giving up his dream or succumbing into villainy. Gets Played With in the finale. While he does end up becoming Oma Zi-O, this is just a temporary state as Sougo sacrifices this power to repair the timeline and bring all of this friends back to life.
- Morgana Pendragon from Merlin. Woobie, Destroyer of Worlds to manipulative, chronic smirker.
- Once Upon a Time: Nimue is initially introduced as Merlin's lover, but her anger at Vortigan sends her on a foolish and self-destructive path to defeat him, which ends in her becoming the first Dark One.
- Al Rawabi School For Girls: Mariam starts out as a very sympathetic protagonist, but by the end she is willing to go to drastic lengths for revenge and her friends turn against her. By the end, she ends up being no different from her bullies, with the only difference being that Mariam, while undoubtedly vengeful and ruthless, also wants to make sure that no one else would ever go through what she had suffered.
- Lex Luthor's journey from good to evil in Smallville is the most prominent plot, second only to Clark's journey to Superman, in the first seven seasons (after the seventh season Lex was left crippled in a disaster that temporarily depowered Clark, leaving him a Dark Lord on Life Support until an alternate version of his father made a Deal with the Devil to restore Lex to full health).
- Season 5 of Sons of Anarchy (and possibly the whole series) is very much about this for Jax Teller.
- E.Z. Reyes in Mayans M.C. goes through an accelerated and far worse version of the same character arc. In Season One he's a former golden boy and new Prospect to the Mayans forced to go undercover and inform on them to earn a pardon for his wrongful murder conviction. Over the course of the first season he slowly slips into the criminal lifestyle, to the point that he chooses to remain with the Mayans after his record is expunged. As a full patch he makes a number of moral compromises to protect himself, his older brother and the club, including killing several people for real, but generally remains a sympathetic Anti-Hero. The turning point is mifdway through Season Four where he murders his innocent ex-girlfriend to prevent her informing on his brother and becomes utterly ruthless. He executes his prison mentor in cold blood, seizes control of the Mayans, aligns himself with his former Arch-Enemy Miguel Galindo and leads the Mayans into an all-out war against the SoA.
- This is one plot line of the fourth season of Supernatural. Sweet, heroic Sam just wanted to save his brother from hell and fight demons, especially Lilith, who was trying to kickstart the Apocalypse. So he started using his demonic psychic powers to exorcise demons and save possessed people. He even manages to stop Samhain from destroying a town and shattering more of the seals on Lucifer's cage. Despite his brother's dire warnings, the audience has a hard time condemning his intentions right up until it's revealed the powers come from drinking demon blood. By the season finale, he's so addicted to the power that he abducts a possessed woman, forces her into a trunk while she pleads for her life, murders her, and drains her body of blood, kills Lilith, and inadvertently lets Lucifer walk free. Much of the fifth season involves his painful search for redemption.
- Tyrant (2014) is very likely this, given that the harmless-looking Western-educated pediatrician protagonist is based on harmless-looking Western-educated ophthalmologist Bashir al-Assad
. Ultimately proven correct when the series was unexpectedly cancelled at the end of season 3. By that point, Bassam al-Fayeed rules the country of Abuddin with an iron fist, has lost or driven away many of the people he cared about, and knowingly plunges the country back into war to destroy the Caliphate insurgent army who killed his daughter. He did turn out to be his father's son. - The German World War II drama Unsere Mütter, unsere Väter has Friedhelm, who starts out as a compassionate if somewhat cynical new Wehrmacht recruit, and is gradually transformed by the horrors of war into a Sociopathic Soldier who willingly carries out brutal reprisals against suspected partisans and civilians.
- Happens to William in Westworld during The Reveal of the show's three concurrent timeframes in "The Well-Tempered Clavier", of which William is involved in two. The 30 years in the past time frame follows him as a milquetoast and heroic young man roped into a company trip with his business partner and brother-in-law Logan. After spending several days being berated by Logan for his heroism when Logan only came there for the debauchery, as well as being forced to do progressively more morally dubious things and culminating in a Breaking Speech from Logan that shatters his worldview, William ruthlessly slaughters an entire camp of Hosts and threatens to kill Logan if he doesn't follow his orders. Cut to the present day, and we see William has become a long time patron of the park known only as the Man in Black who ruined his marriage and devolved into a violent, raping sociopath in his quest to find the true meaning of the park.
- Why Women Kill: Alma increasingly becomes more malevolent as soon as she buries Mrs. Yost in her gardens. Her dream to just be in the garden club motivates her actions the most moving forward, as she is unwilling to let anything ruin that to the point of theft. However, her breaking point is when Rita's Disproportionate Retribution shuts her out of her dream club. Eventually, her opinion is Murder Is the Best Solution as shown with the murders of Carlo and Isabel just to keep her garden club position, as even Bertram knows her true reason for murdering the latter.
- Wolf Hall frames the career of Thomas Cromwell this way. He starts off as a man with a rough past who finds a job doing legal work for Cardinal Wolsey. He has many sympathetic qualities, a loving father and husband, a Self-Made Man who is loyal to Wolsey until the end and Nice to the Waiter besides. He enables Henry's marriage to Anne Boleyn and enacts policy with efficiency and ability. But when Henry turns on Anne, Cromwell is motivated not only by the lesson of Wolsey's fate but because he sees an opportunity to avenge the men who (indirectly) caused Wolsey's death and then jeered it. He orchestrates the Kangaroo Court and uses the whim of a tyrant to avenge a long-ago insult—the final scenes of the series indicate that he's well-aware of what he's done and is not particularly happy about it.
