Highschool of the Dead has several of these. None so far have tried to hide it, and most of them get put down by the heroes or die by their own hand after expressing a firm desire to die rather than become one of 'them'. The first arc of the outbreak in particular features two infectees (Hisashi and the boy in Shizuka-sensei's office) who are Mercy Kill'd. It's probably happened a few times off camera, though, since we see that "they" have somehow gotten aboard Air Force One.
Happens unknowingly in Garth Ennis'... strange book Crossed. One member of the party is shot (the eponymous Crossed are intelligent, just psychotic), and seems to just be in shock. However, there's quite a Oh Crap moment when a scouting party witnesses a group of Crossed soaking bullets in their semen. Cue rampage.
Mostly averted in The Walking Dead. Most survivors are sufficiently paranoid and genre savvy to be on guard, and most infectees either decide to be left behind or take the "third option" described above. On the negative side, it has also been shown that the recently dead can and probably will rise as zombies even if they were not directly infected by another zombie. An interesting variation on the trope has occurred several times, when certain survivors remained in deep denial and refused to distance themselves from their fully infected loved ones.
In fact they now operate on the idea that bites DON'T infect them with a zombie virus and that if the wound is treated properly (Which unfortunately in the post apocalyptic Walking Dead verse means amputation) the person bit can live.
The weird but excellent Zombie Apocalypse/House fic "The Rampant Disease" features an infectee House refusing to let his love interest kiss him because they know The Virus is spread through bodily fluids. (That the story also contains two of the more egregious instances of Die for Our Ship ever seen detracts slightly, but it's still a great story.)
There's a Fullmetal Alchemist fanfic called "Mistakes" where Mustang becomes an infectee after getting bitten on the wrist and refuses to admit what bit him. Despite admitting the truth eventually, Mustang averts the trope by being cured when his totally infected arm gets torn off by the Gate.
Happens to several characters during the DC Nation version of Blackest Night, most notably to Troia and Oliver Queen.
The Resident Evil movies have examples of good and bad Infectees. Notably, a recurring minor character from the second movie, Ethnic Scrappy L.J, is bitten in the third. What's infuriating about this example is that the movie is set well after the zombie plague has swept through the world, so he couldn't exactly plead ignorance; L.J. had likely seen the same thing happen dozens of times. And yet he keeps his infection a secret, even as he begins to sicken. Once he turns (which inconveniently happens during the big zombie attack), he almost kills The Chick while both are locked in a car, and then infects one of the likable main characters, who does the right thing and takes as many zombies with him as possible in a massive explosion.
Played with in the character of Shaun's mother in Shaun of the Dead. She waits until just before she dies to reveal she's been bitten, but not necessarily to save her life; rather, she wanted to keep the burden off Shaun for as long as possible, explaining: "I didn't want to be a bother."
Whereas Shaun's friend Ed, after being bitten, does a Heroic Sacrifice by staying to hold the zombies off while the others escape.
The "Sex Machine" (played by SFX guru Tom Savini) in From Dusk Till Dawn hid his rapid vampirization for fear of being killed. Fortunately he was killed without much problem. Unfortunately he let all the other vampires in.
On the flip side, badass ex-preacher Jacob is open and frank about the fact that he's been bitten and doesn't have long, and was pretty emphatic in getting his kids to do him in when the same was happening to him.
In the 2004 remake of Dawn Of The Dead 2004, pregnant Luda gets bitten. Once her husband Andre discovers the bites turn the victim into a zombie, he sets his wife up in the maternity store, separate from the other survivors. Andre sinks so deeply in denial that he refuses to accept the truth, even when it's obvious The Virus has her; instead he becomes her twisted caretaker. Ironically, Luda doesn't kill anyone, because Andre restrained her when she went into labor (during which she died and reanimated). When Norma discovers zombie Luda, she shoots the undead new mother. Norma and Andre then exchange more gunfire, killing each other. Ana then arrives and shoots Luda's newborn zombieinfant.
Additionally, Frank, once informed that the bites are going to turn him into a zombie, elects to be separated from the others, knowing he will be killed when he reanimates.
Subverted when Michael gets bitten and stays behind, knowing he can't accompany the rest of the survivors beyond this point. It's not quite a Heroic Sacrifice, but he at least displays consideration for the other survivors' safety. It is instead Ana, the woman Michael loves, who goes into denial, insisting she can help him because she's a nurse, even though she knows full well the consequences and wasn't able to do anything for any of the other infectees in their recent acquaintance.
In the original version, Roger is bitten and knows full well what is coming. He asks Peter to let him succumb, and then wait and see what happens as he is going to "try not to come back". It fails, and he is killed upon rising.
In Land of the Dead not a single infected person hides their status; if they are bitten they commit suicide or die fighting. However, the prize goes to Chollo, who is just about to abandon the city when he unexpectedly gets bitten. He's been on a zombie-killing team for years, so he knows what's coming. His right hand man asks if he wants to be shot or shoot himself. Chollo chooses neither, but instead goes back to Fiddler's Green, intending to take his flesh-eating revenge on his Corrupt Corporate ExecutiveBad Boss Kaufman.
Averted in 30 Days of Night, when a widower not so slowly turning into a vampire asks to be killed not only to avoid becoming a murderer, but because he can't stand the thought of being immortal and never dying to see his family in heaven.
Further averted by sheriff Eben Ouleman willingly infecting himself, and then using Heroic Willpower to fight and kill the vampire leader. Sadly he sacrificed himself by waiting for the sun rather than risk losing his self control and becoming a monster.
Played straight however when a man hiding under a house slowly turns into a vampire before finding Eben and trying to kill him.
Several people in the Return of the Living Dead series keep their wits about them once infected. They even find ways to stave off the desire to eat flesh well into the transformation phase, so as to not be a danger to friends and loved ones. This, unfortunately, makes them rather attractive to the government.
Averted in Grindhouse: Planet Terror. Cherry is attacked by zombies who bite her leg off. After getting medical attention, she proves to be immune to the neurotoxic agent causing the zombies, as are most of the other leads. Others, not so lucky, are infected not through bites or scratches, but through the infected smearing bodily fluids on them. Ew.
Mostly avoided in Diary of the Dead. Everybody who gets infected has the wisdom to blow their brains out before they can rise. There were only two straight examples in the entire movie where characters rose after death.
The very beginning. Gordo gets bitten, and dies. His girlfriend is of course in shock, and claims he might not rise. The group doesn't believe her, but this is the beginning, so they aren't sure, and they leave her to grieve. He does eventually rise, but she reluctantly shoots him in the head instantly, before he cause any trouble.
Jerk Ass Ridley, who was in the horror movie at the beginning of the Zombie Apocalypse they're blog-documenting, is seen early on partying with his girl. He invites the film crew to come join him because they're perfectly safe where he is. By the time Jason and company get to him, he's all alone and acting erratic, even for him. Only when Deborah convinces him to tell her where everybody else is does it become obvious that he's infected.
A third example comes from one of the video asides. A team of armed soldiers raid a house where a live family is storing their infected relatives. Over the family's protests, the soldiers open the room where they've been storing the zombies and shoot them, but the father's interference causes the sergeant to be bitten. Incensed, he deliberately shoots the living family members in the hearts so that they will "wake up dead."
While not a zombie plague, in Blade II one of the vampire strike team, Lighthammer, gets bit by one of the "super-vampires" and covers it up (surprisingly well considering he's one of the most underdressed members of the team), until he predictably turns and starts gobbling up the rest of his team.
Although not technically zombies, the 'Rage' victims in the 28 Days Later movies deliberately avert this trope; the virus infects and converts its victims within 30 seconds to a minute, thus preventing them from concealing their condition from those around them. It also ups the tension, as the non-infected have to deal with the victim immediately in order to save their own lives.
The first movie also offers a potential inversion; after butchering a number of infected, one of the characters discovers that he's somehow received a cut. As there's so much blood — both his and theirs — it's unclear as to whether he's actually been infected. This doesn't stop one of the other characters from instantly butchering him with a machete.
In another vampiric variation, Montoya in John Carpenter's Vampires also hides his own vampire bite. His subterfuge does not really matter, as he gets bitten again later in a less discreet place.
Quarantine involves a news crew and a group of firefighters locked into an apartment complex with a bunch of other people and a zombie infection. They store the infectees in the same room that most of the living people are congregated. Guess what happens?
Averted, then subverted in Zombieland. Little Rock appears all too willing to take the bullet to avoid being a danger to other survivors but it was just a con to let her and Wichita steal the guys' car and guns.
Played straight, however, with 406, but to be fair nobody knew about zombies or The Virus. She just thought some crazy homeless guy attacked her. Plus she only says he tried to bite her, not that he actually had. Considering everyone seems aware of how zombies work, she might have been afraid of being shot for this very trope.
As the title might suggest, this is the entire point of the movie Carriers. While you don't turn into a zombie, the plague's extreme contagiousness makes you just as much of a threat. After being infected, Bobby plays this trope painfully straight, until being abandoned with a little water and directions by her boyfriend. When he in turn is infected, he initially forces his companions to carry him, and then makes his brother shoot him when they try to escape, rather than leaving him to die a slow death.
Subverted very humorously in Dead Snow: One of the characters gets bitten on the arm. He knows what he has to do, so he slices off his arm with a chainsaw to stop the infection from spreading to the rest of the body. After a really painful looking scene and a sigh of relief, another Nazi zombie pops his head up from the snow and bites him on the crotch. He kills that zombie and looks back to the chainsaw in horror.
Amusingly averted in Flight of the Living Dead, when one of the protagonists gets munched on by a little old lady zombie. It looks like the story will go this way, as the character is a criminal out only for himself, but the aversion comes in when it turns out the biting zombie doesn't have her dentures in and didn't penetrate his skin.
Dog Soldiers has three werewolf infectee's each with different reactions.
World War Z makes these a larger threat than the living dead. A zombie is not particularly dangerous to anyone with a gun, but the infrastructure behind an army - zombie-hunting or otherwise - does not cope well with things like mass panic and refugee columns that contain an unknown number of infectees unaware of or unable to cope with the facts. (A bonus: imagine the rumor mill about immunities and cures.) Dogs can smell The Virus, and it freaks them out. In a controlled refugee situation, anybody a dog reacts badly to is taken aside as infected... often to the loud and increasingly histrionic protests of the infectee in question. Uncontrolled versions feature a lot of improvisation, but one option is to separate the zombies and the uninfected with a mass nerve gas attack.
The nerve gas attack "separates" the infectees out because while the gas kills everyone, only the infectees will stand back up... Ugh.
Arguably a case of Truth in Television: Some people in the Middle Ages would protect themselves from the Plague by finding a remote hideout and shooting anybody coming too close with a crossbow in order to avoid contact with potential infectees.
When the militaries of the world finally started clearing towns the most dangerous zombies were those that had been "kept" by their families. These Zeds were usually inside of closets or wardrobes in otherwise safe towns and could create a very nasty surprise for a soldier with slow reflexes.
Further, in an aversion, people could become infectees completely by accident or unfortunate happenstance; and would do the right thing. One soldier knew he had to be put down because someone shot a zombie. The bullet went through the zombie, then into the soldier, bringing the infection with it. in Russia this becomes the responsibility of army chaplains, one thing leads to another and the country ends up a theocratic empire.
Averted when one interviewee tells of a buddy who was bitten and turned into an instant emotional wreck, knowing full well he would have to be put down, making no attempt to avoid the reality but is simply unable to take it standing up. It turns out the biter was a Quisling, someone who lost their marbles on the face of the Zombie Apocalypse and acts like, but is not, a zombie. The victim breaks down crying in relief. Ironically, he nearly dies from a Staph infection from the bite.
There were rumours of cures, and immunity - mostly fueled by the Quislings, and the fact that it was possible to survive being bitten by one of those, but not by a real zombie. Early in the book, one of the interviewees - a guy who dealt in smuggling people across the borders, mostly by car - mentioned that he suspected a lot of outbreaks in other areas were caused by infected getting out of China through the smuggling routes he and people like him used and then going to ground in the ghettos in other countries. He mentions that he regrets letting them get through, on his watch, and that he believes that most of the infectees (and their families) were trying to get out and find a cure - not because they actually believed there was one, or because there was any rumour that one existed, but because they were desperate and clinging to any straw of hope they could find, that they wouldn't have to take that final option.
Of course the cure rumors weren't helped by the fact that the zombie virus did have a drop in number infected the first winter of the crisis, a corrupt businessman linked it to his placebo antivirus (it was just vitamin pills) which created a false sense of calm. In reality the drop was due to the colder weather making zombies in places like northern Europe freeze solid for a couple of months and by limited operations from military commandos to slow down the rate of infection. Unfortunately government budget restraints stopped the U.S. (and presumably most other nations) from starting a dedicated offensive until it was too late.
Near the end of Stephen King's short story "Home Delivery", itself an homage to the films of George Romero, a member of a group of zombie hunters who help protect a small island community realizes he's having a fatal heart attack, and demands that his fellow hunters shoot him in the head (after he completes the Lord's Prayer) so that he doesn't rise immediately after he dies.
Head? No, that wasn't sure enough for him. He arranged for them to shoot him in all vital organs SIMULTANEOUSLY.
In George Romero's short story "Anubis", plunging a knife into the brain of a dead person is part of the funerary rites—-note that Romero revenants are not infected with a zombie "virus", it's just that the bite of a zombie is fatal, and everyone who dies rises.
The rabies variant shows up in The Call of the Wild. At one point, the group is attacked by a pack of rabid dogs, but apparently make it out alive. Some time later, one of the sled dogs goes mad and has to be put down.
Parodied in the Community episode "Epidemiology" when a zombie plague hits the campus. Rich (a doctor) hides being infected among the main characters and doesn't reveal it until he starts turning, as he thought "it made him special." A jealous Britta then reveals she was bit too and immediately starts turning as well.
Subverted in In the Flesh, where the only Zombies to exist were individuals who died in the year before the Rising. However, due to multiple zombie tropes being ingrained into people's heads through pop-culture, there is a widespread belief that anyone who died during the Rising will come back as a Zombie (they don't) and you can become a Zombie after being bitten (you can't).
The player character acts like a werewolf version of this in the worgen starting zone in World of Warcraft. After getting bitten by a worgen, you get a debuff 'worgen bite', which is described (at first) as 'probably nothing'. (Checking back on this debuff every so often reveals that it's slowly getting worse.) Your character doesn't mention anything about this wound to anyone until you transform and go nuts. Unlike most examples of this trope, you get better - an NPC gives you an experimental treatment that restores your human mind inside a worgen body. Later, thanks to intervention from night elf druids (and an artifact previously thought lost), you gain better control over your worgen powers, which provides your racial abilities.
Subverted in The Walking Dead video game, when Kenny Jr., aka Duck is bitten, no one hides it. It's less of an issue of denying the bite, but rather the parents coming to grips with the fact that they're going to have to kill their son.
The player can hide the identity of the next bite victim from the group or not because the infectee is the protagonist, Lee. In what is one of the biggest heartwarming moments in the game, if Lee reveals the bite, it can convince Christa and Omid to come with him to rescue Clementine.