The Witness Protection Program serves to, well, protect witnesses to crimes in order to prevent perpetrators from... cleaning up after themselves, in a way. To put it simply, in case the perp has ideas to eliminate the witnesses in question, the Witness Protection Program will take those witnesses and officially alter all their records and form new identities plus have them move to another location in order to make them virtually impossible to track by the offenders. In Real Life, the program tends to be fairly successful in granting these people the security they need because there are multiple levels of protection and doesn't have to be a new identity, such as adding restrictions on who can read normally public records. But in fiction...that's another story.
In fiction, if someone is placed under witness protection, they might as well have just pasted a huge "KILL ME" sign on their back because chances are that character is going down, courtesy of the perpetrator in spite of all the odds. Exactly how the bad guy finds these people regardless of all their records being virtually erased is rarely ever brought up. Perhaps the perp had some help from the inside? Or maybe the perp has supernatural abilities that aided their search. Or maybe the people who are SUPPOSED to be keeping their identities secret aren't that good at doing their job. Or perhaps they just happen to be a Scarily Competent Tracker. Whatever the case, they will find a way to get to these witnesses, government protection be damned.
Sometimes, the witness will be lucky enough to survive the inevitable attempt on their life (usual reason being them being a main character), but that still means the witness protection failed; the perp found them anyway. Fortunately, should the witness survive, what usually follows is either the bad guy getting killed and the witness being able to return to their old identity (which isn't possible in Real Life witness protection), or the bad guy getting incarcerated, which usually only delays their inevitable return.
In cases where a government-issued program does not exist, friends, relatives, and associates of the witness may make their own form of protection. However, the chances of the witness getting found out only increases exponentially. Especially if the protectors happen to be particularly powerful.
The Anthropic Principle is in full force here; if the witness protection did work, the characters would simply happily disappear into their new lives, and there would be no story.
Not related to the Larry the Cable Guy film Witless Protection.
- Played for Laughs in this Dutch commercial for an insurance company. A man testifies against a mob family and is placed in the witness protection programme. But no sooner has he settled in his new house, his cover is blown because he is the 100.000th new inhabitant of the town where he settled and is greeted by a huge welcome committee, complete with tons of press coverage.
- Played for Laughs in a commercial for A&W Root Beer, someone is being driven by Witness Protection in a car with giant "witness protection" lettering printed on the side. When a car full of mafiosi tailgate the witness protection car, the driver says "Hold onto your hats, I'll shake them" and very slowly changes lanes.
- Averted in Detective Conan, there is a character called Jodie Starling who changed her name from Starling to Saintemillion due to this actress named Vermouth killing her parents and searching for Jodie. Jodie initially rejected the offer of Witness Protection by the FBI, but then changed her mind and it helped protect her. What changed her mind was making a promise with James Black to look for her parent's killer when she's old enough to join the FBI. The Witness Protection was successful, and she survived to adulthood and became an FBI agent.
- In the The Authority: Kev series, Kev Hawkins' address is supposed to be a secret due to his history with the SAS, but he keeps getting found by the various Irish terrorist groups who want him dead. It's later revealed that his handler, Froggett, deliberately leaks his location to his enemies in the hopes that they'll kill him and thus Froggett will finally be rid of Kev once and for all.
- Batman: Officer Down has a rare case of a completely unsympathetic witness — a former mafioso who resented being split up from his family (never mind that it was his choice to join the mob to start with) and guns down Commissioner Gordon for arranging the State's-Evidence deal to begin with. Ultimately, even Batman's unable to make him confess to the shooting, and he walks... until Bullock deliberately leaks his identity to some of his old associates.
- In The Trial of The Punisher, Frank Castle allows himself to be arrested and put on trial because he wanted to explain something in his defense: that he knows the judge presiding the trial used to be a high-ranking mafioso that provided evidence to the FBI and entered Witness Protection, and thus escaped punishment from the law — but not from Frank, who had already killed the corrupt DA that got the mafioso the deal before letting himself be captured, just to get in this room. The judge only has about two seconds to crap his pants before Frank gets out of his cuffs and unleashes the most literal example of "Rage Against the Legal System" ever.
- Saga: Journalists Upsher and Doff know of a program to protect testifiers, that doesn't just change their identity but also transfers them into a completely different body to make them harder to trace. While Alana and Marko turn down the offer, Petrichor and Robot IV take it, Robot giving a testimony about the real circumstances behind the destruction of the planet Phang.
- One The Far Side strip has an informant interviewed on TV (in a darkened room)... so of course, a janitor comes in and turns on the light right when they cut to the guy.
- Parodied in Osmosis Jones - at one point the crew visits the Chicken Pox virus who says they are in the virus protection program. This is actually a case of Shown Their Work - the virus that causes Chicken Pox actually does lie dormant within your nerves after infection. At the age Frank is, it's very unlikely that he was vaccinated against Chicken Pox, thus he would have a dormant virus.
- Bird on a Wire: Rick is recognized by his old girlfriend and immediately calls his handler, asking to be moved again. He's told his old handler has retired and introduced to his new handler... who promptly sells him out to the bad guys.
- Bullitt begins with Lt. Frank Bullitt and two other cops getting assigned to guard detail for Johnny Ross, who embezzled from the mob and is now testifying against his former employers in exchange for immunity and witness protection. Ross acts like he doesn't understand how much danger he's in, and when he unchains his hotel room door, two hitmen burst in and fatally shoot him. Bullitt smells a rat and investigates further, hoping to prove Ross's death didn't result from his department's negligence. He finds out that it was a setup—by Johnny Ross, who was playing both the police and the mob to fake his own death and disappear. The police never even met the real Ross; the man they were guarding was actually Albert Renick, a lookalike who Ross tricked into taking his place. And Ross was the one who tipped off the mob hitmen on which hotel to find him at.
- Casino: One of the mobsters managed to get on Witness Security and leave the country (ending up on Costa Rica), but his son is arrested and the rest of The Mafia, fearing that he will blab more info on the group, finds him and kills him.
- The Dark Knight: Batman kidnaps a mob accountant and turns him over to Gotham police, and the accountant agrees to help the police bring the mob down in exchange for amnesty. In response, the mob hires The Joker as a "problem-solver"; Joker proceeds to get himself arrested, blow up the police station with a cellphone bomb, spring the accountant from his cell and execute him by immolating him with gasoline.
- Invoked Trope (by the villains) on Eraser: Turns out that the Government Conspiracy that is selling out the Rail Guns has members within Witness Security, and so they are able to hunt down and try to kill (and successfully kill one of) the witnesses holding information on the secret arms sale. The Batman Cold Open that establishes the tactics of John "Eraser" Kruger happens because Johnny Casteleone (a Mafia informant that entered the Program and becomes a Chekhov's Gunman) decided to risk being found by the Mafia to go back to his favorite pasta place and eat his first proper (by his standards) meal in months.
- The '90s B-Movie Made Men starts with Bill Manucci, a Con Man in Witness Protection, getting a phone call warning him that the criminal syndicate he used to work for has discovered where he is and has a group of men already on their way to retrieve the money he stole from the organization before informing on them, after which they will surely kill him. Bill then has to play his old comrades, the local criminals, the corrupt sheriff, and one guy in the group sent after him who claims to be an undercover cop against one another in order to survive.
- In the third act of Malavita, the Mafia family that has been hunting down the Manzonis ever since Giovanni (the father) provided State's evidence manages to find out that the Manzonis are hidden in a small town in France by a collection of Contrived Coincidences involving Giovanni's son writing an article using a quip his father liked to use in his Mafia days for his school paper and a copy making it all the way to the United States and the hands of the Don.
- My Blue Heaven has two instances of the bad guys finding the informer (under witness protection as Tom Wilkinson). The first time is when he decides to go out dancing with his FBI handler and attracts too much attention. The second is when he is caught committing crimes in the small town he's been hidden in and the assistant district attorney indicts him under his real name. Another failing of the witness protection program is that they seem to relocate all of their witnesses to the same half-dozen small towns.
- Our Lips Are Sealed is a Mary-Kate and Ashley Olsen movie in which the sisters' characters have witnessed a Mafia crime and are placed in Witness Protection. Unfortunately for the Program, the girls' attempts at sticking to their faked identities is a total Epic Fail (and even in one point, they broke cover by shouting out to a crowd that they were in Witness Protection because they really didn't like the fact that they were assigned to an Amish community). And so after a Failure Montage, Witness Protection finally went "screw this" and placed them in Australia, with the explicit warning that if they screw up this time, the Program will just wash their hands and let them suffer whatever comes (up to and including getting killed by the Mafia).
- Princess Protection Program is a fictional princess-specific equivalent to the people protection program, and as such during this movie, the program fails to protect Princess Rosalinda, even as it moved her from South America to a small town in Lousiana. She's discovered when the Alpha Bitch finds an article about her in a magazine and recognizes her immediately, then calls up her country to let them know where Rosalinda is.
- Runaway: One of the few leads the police gets to find Big Bad Dr. Charles Luther is Luther's girlfriend Jackie coming to the police looking for witness protection (because she is both running away from his abuse and took the patterns to create more killer-program chips, derailing his Evil Plan). Unfortunately for Jackie, Luther is a supreme expert in Hollywood Hacking and Crazy-Prepared (having concealed multiple bugs in her clothes) and she doesn't survive the night.
- Justified in Sister Act, where the main character under witness protection is found by the mob thanks to a mole working inside of police headquarters. The police know (or at least suspect) the leak exists, but it takes some time for them to find and plug it. Unfortunately, the mole finds the protagonist and reports her to the mob just before he gets caught. Also downplayed in that it takes most of the length of the film for the mole to find her in the first place.
- Arrow: At the start of season 7, Felicity Smoke and William are in ARGUS witness protection program since Diaz, the Big Bad of the previous season, is still out to get them. naturally, he tracks them down and almost kills them both, prompting Felicity to send William away to a boarding school in Cambridge, and herself to return to Star City and reunite Team Arrow to take down Diaz herself.
- Better Call Saul features a fascinating, almost complete inversion of this trope: Season 3 involves the construction of a meth superlab using foreign contractors. The contractors are carefully vetted and hired by Mike, who supervises them in a secure location while they do the work (living in a warehouse almost like a government safe house). The contractors all have cover stories and don't know where they are geographically. When one naively exposes the operation to possible discovery by both the DEA and a rival cartel, Mike is forced to execute him and is shown to be greatly upset by it.
- Subverted in Brooklyn Nine-Nine. After receiving death threats from Jimmy Figgis, Jake and Holt end up living in Florida under witness protection. They manage to live there under the false identities of Greg and Larry for six months and are often checked up on by their Marshal. However, the two intentionally break several rules to lure Figgis to Florida in order to finally apprehend him and resume their lives in New York.
- In the Doctor Who serial "The Ambassadors of Death", a scientist called Lennox runs away from where he's been held and forced to do alien experiments and turns himself in to UNIT. His superiors are quick to find out where he is and murder him by putting a radioactive isotope in his cell.
- FBI: "Compromised" sees Maggie and OA dealing with several people in the Witness Protection Program getting exposed and assassinated in rapid succession, even several who have already spent years within the program without a problem. It's acknowledged in the episode that this has never happened before and shouldn't be possible. It turns out the local head of the US Martials running the program is corrupt and is selling the information for money.
- This turns out to be the case with Rose's boyfriend Miles in The Golden Girls, as he was really a mob witness named Nicholas, on the run from a boss named The Cheeseman. Later he returns with a new identity as an Amishman, only for Rose's new boyfriend to be the Cheeseman, recognizing Miles and holding everyone hostage until their neighbor, a cop, comes in to save them.
- The Green Green Grass: Invoked. Boycie ends up having to flee his beloved London, following it being leaked that will he testifying against the Driscoll Brothers. As such he sells everything and buys a farm in Shropshire, then leaves in the middle of the night without telling anyone. When Marlene asks why not go into a Police witness protection, Boycie points out it was the Police who told the Driscolls he was the grass. The Driscolls do eventually find him, but only after Marlene foolishly invites her sister to visit for the weekend, up to which point they admit they had no clue where he was.
- In Plain Sight zig-zags with this trope. Many times the protection's secrecy breaks because of the witnesses being Too Dumb to Live (or something else happens, like a recording where one appears becoming a YouTube sensation), and sometimes because of inner leaks or because the bad guys are that much of an example of the Implacable Man.
- A mob turncoat from Law & Order is under federal protection pending his testimony against a criminal kingpin. The turncoat gets shot dead in an alley by his date, who pleads self-defense against an attempted rape.
- Series 2 of Line of Duty begins with the murder of somebody in witness protection, and the plot of the series is basically the investigation into that murder.
- In The Mentalist episode "Red Sauce", the Victim of the Week is a mobster in Witness Protection after testifying against his boss. His wife did it because he cheated after she gave up everything for him.
- In Person of Interest, Samaritan leaks the entire witness protection database onto the Internet as part of its war with the Machine. The NYPD spends most of a day struggling to reach the people in the WPP and get them into protective custody, but several are killed.
- The Police Woman episode "No Place to Hide" has hit men working under the guise of a detective agency taking down former mob witnesses. One of them has a girlfriend working on the inside to provide information on the targets.
- The backstory of Signed, Sealed, Delivered episode "Time to Start Livin'" has a boy riding his bike down an alley and stumble onto a lowlife narcotics ring just before a shooting. He became the star witness and he and the family had to hide out at some undisclosed location until he could testify against the criminals at the trial. In the episode proper, the baddies use a female agent to extract the location from a letter the boy secretly sent to his grandmother in an elderly home. The heroes catch up with the agent and prevent her from reaching and killing the boy.
- In the Taxi Brooklyn episode "Ambush", a witness in a mafia trial is being transported via a prison bus that gets hit by mobsters, even though she was traveling under an assumed name. Subverted somewhat in that the mobsters don't know her real name or what she looks like, so WITSEC at least didn't screw that part up.
- In one episode of Veronica Mars, Veronica is unintentionally manipulated into tracking down a man in the Witness Protection Program, thinking she's helping a woman find her ex-husband. It wasn't very difficult for her to find out who he was and where he lived, and almost gave the woman the man's home address before her father stopped her and told her who she was actually aiding.
- Witness Protection rarely works out for anyone in The Wire. Because the city is so broke that it can't afford a proper witness protection program, on numerous occasions over the course of the series witnesses are killed or people who try to come forward with evidence of crime unintentionally give themselves away to their fellow criminals and pay a heavy price as a result.
- The Saint short story "The High Fence". A captured criminal agrees to turn Queen's Evidence and tell the police who the High Fence (an underworld buyer of stolen goods) really is. He's murdered in his cell by being fed poisoned food. When another criminal is taken into custody and agrees to tell Inspector Teal the High Fence's address, he's shot dead before he can do so.
- Tommy Angelo, the protagonist and narrator of Mafia: The City of Lost Heaven, trades in his mafioso secrets for a new identity under the US WPP. His old mob cronies find him twenty years later, anyway, and shoot him dead in the epilogue.
- In Police Quest 2 escaped convict Jessie Bains is getting his revenge against the protagonist Sonny Bonds, the cop who arrested him, and the three witnesses who testified against him. One of the witnesses, Donald Colby, is under Witness Protection, and Bonds even gets a warning to him and the police of the city Colby is in. Nevertheless, Bains manages to kill the witness. Of course, it didn't help that Colby still used his real name and even opened a business under it, allowing Bains to easily track him.
- Saints Row 2 has a side mission where you have to assassinate a guy in WPP, which is as easy as going to the next fast-food, ordering every item from a menu to lure him out, and shooting him and his two bodyguards (both basic cop NPCs) dead. This is justified by the police in Stilwater being both extremely corrupt and extremely incompetent.
- In Family Guy, Chris becomes a witness in a robbery and anonymously sends the thief to prison, however, his identity is spilled to the robber twice by both Peter when he wanders into the wrong room looking for his son, and also by the FBI when they give the robber the Griffin family's new address in Dixie.
- In Futurama, Bender has to go into witness protection after he agrees to testify against the robot mafia. The detective in charge of the case directly tells Bender that the mob will find and kill him. Bender survives only because the mob mistook a similar-looking robot for Bender. No credit to the detective, though - his 'relocating' of Bender consisted of getting Bender a job at the pizza place across the street from his previous employer.
- The Simpsons episode "Cape Feare" is a Whole Plot Reference to Cape Fear and as such the program does not work out. Sideshow Bob threatens Bart to kill him so the family decides to go into witness protection until Bob is sent back to prison. The relocation agents name the family the Thompsons and tell them they'll leave Springfield to begin a new life in Terror Lake. The family drives to Terror Lake and move into a houseboat, believing they are safe from Bob. Bob, however, has belted himself to the bottom of their car. In Terror Lake, Bob resumes his threats to Bart.