How to Survive An Encounter With the Infected 'Zombies' of <i>The Last of Us</i>

Welcome, students of The Last of Us, to Fungus Zombies 101. In this seminar, we’ll cover the basics of what’s known as the cordyceps infection, how it spreads throughout a host’s lifetime, and why it ought to haunt your nightmares. Ready? Let’s dive in!

In the HBO show The Last of Us—and the 2013 and 2020 PlayStation video games that inspired it—the zombies are not, in fact, zombies. (At least, not in the traditional sense of the word.) These walking dead never actually died, nor were they ever reborn; instead, a terrifying fungus crawled through their insides and took over control of their still-living bodies. Thus, the proper term for these creatures is “infected,” though “fungus zombies” is an oft-accepted colloquialism. (Just don’t tell game developer and show co-creator Neil Druckmann.)

There are four main stages of the cordyceps infection in The Last of Us, plus one bonus stage we’ll get to in a bit. Each stage will only progress further after meeting the right conditions, whether it be time or environment. If those conditions aren’t met, some infected will remain in one state for longer periods; others will die before they’ve had the chance to evolve through the final stage. Regardless, all stages of infected are violent, bloodthirsty, and capable of spreading the fungus through bites, spores, or—in the show—long tendrils of mushroom-like stalks. If that’s not enough to stir your survivalist instincts, read ahead for a few more reasons why you should invest in a good bunker.

In The Last of Us, there’s only one real hope against this wave of wobbling monsters: Ellie (Bella Ramsey), a teenager who’s showcased immunity against the fungus. In season 1, the weathered smuggler Joel (Pedro Pascal) escorts Ellie to a group of rebels known as the Fireflies, who want to develop a vaccine from Ellie’s brain tissue. But when he learns that the surgery would kill Ellie, Joel wipes out the Fireflies and rescues her—without telling her the truth of the encounter. In season 2, both Joel and Ellie deal with the fallout of that choice. And they still have to contend with the infected.

Therefore, you’ll want to know the difference between your clickers and bloaters. Below, we’ll run through the types of infected—and dole out a few tips on how to outlive them. Study up, and mayhaps stay away from pancake mix.

Stage 1: Runners

Runners are the most humanlike of the infected, largely because they’re the most recently “turned.” Within two days of a bite (or breathing in a healthy dose of spores), but sometimes within hours, a human will lose control over their faculties and transform into a runner.

At this point, the fungus hasn’t yet had the chance to spread throughout the body and pierce the skin, so while runners’ minds might be a lost cause, their bodies still look deceptively human. You’ll know them, instead, by their hair loss and diseased-looking skin; their erratic, jerky movements; the snarls and screams that erupt unprompted from their throats; their torn, stained clothing and bloody mouths; and—if you dare look close enough—the tendrils of cordyceps that sometimes emerge from between their lips.

In the video game, runners are the easiest group of infected to kill, though they tend to attack in groups and move at extreme speeds (thus the moniker “runner”). The runners in the HBO show exhibit similar tendencies: In the series premiere, a runner chasing Joel and his daughter is so quick it seems almost supernatural. But because these monsters have yet to develop any fungal armor, runners are susceptible to gunshots, knives, and any other weaponry that would take out your average pleb.

The internal awareness of runners is the subject of debate in the world of The Last of Us, but there’s evidence runners are still “awake” enough to recognize they’re no longer in control of their own bodies. (Some runners moan and shriek in agony even when they’re not under attack, and others seem resistant or even remorseful over their gory instincts.) It’s an ugly premise, one the show touches on when, in season 1, episode 5, a newly infected Sam asks Ellie, “If you turn into a monster, is it still you inside?”

Stage 2: Stalkers

Usually after two weeks post-infection, runners shift into stalkers, a stage they can remain in for more than a year. At this point, fungal growth becomes visible on their bodies, peeling away skin and bursting through orifices. (If you get close, pray you have a good gag reflex. In season 1, episode 2, Tess learns this the hard way.) These creatures begin to lose their humanlike sounds and instead emit croaks, though they’re still quiet enough to hide, track, and attack their victims, earning them their “stalker” title. For this reason, they tend to prefer locations with plenty of places to hide; bonus points if it’s dark and moist, as Ellie and her friend, Riley, discover in season 1, episode 7.

Stalkers are also stronger than runners. By this stage, they’ve sprouted the beginnings of what, in essence, is mushroom chainmail. A simple fist fight ain’t gonna cut it, so shotguns and flamethrowers are often a better pick if you’ve got an arsenal at your disposal. Ellie managed to take one stalker out in episode 7 with a knife, but that was only after both she and Riley endured bites, so...glean from that what you will.

Oh, and beware getting too close to a stalker that already seems deceased. The creatures are capable of temporary dormancy. They can attach themselves to buildings while they nap, allowing tendrils to emerge from their bodies and climb the surrounding walls. If awakened, they can break out of this shell and attack again. Others remain in this state until the cordyceps fully consumes their bodies and they die.

Stage 3: Clickers

After the first year of infection, stalkers phase into clickers, arguably the most iconic of The Last of Us inventions. They first appear in the second episode of the HBO series, when Ellie, Joel, and Tess creep through an abandoned museum together. With enormous mushroom blooms splitting open their skulls, clickers are more fungus than human—with the exception of their mouth and teeth, which remain intact to snap at victims. You better believe that breath is foul.

Because the cordyceps has either covered, disfigured, or entirely done away with the body’s eyes by this stage, clickers are blind, but they make up for their inability to see with a bone-chilling form of primitive echolocation. The croaks that began in the stalker stage now become “clicks” as the infection spreads, and the clickers use this sound to locate humans and communicate with other infected. This ability is imprecise, sure, but that doesn’t make it any less creepy.

When aware of a potential victim in their midst, clickers are obsessive, utterly consumed with the task of finding (and gnawing on) the errant human. And when surprised or attacked, all bets are off; they go “berserk,” and you’d best have a really dependable firearm in your back pocket. (Or a Molotov cocktail! You carry those around all the time, right?) The better option is to try and outsmart them, sneaking away silently so as not to trip their unsophisticated echolocating alarms. Much stronger than runners and stalkers, clickers are tough to kill and even tougher to expunge from your dreams. Good luck!

A particularly pissed-off clicker.

Stage 4: Bloaters or Shamblers

Several years post-infection, stalkers grow into either bloaters or shamblers, seemingly depending on the environment they grew up in. (Nature versus nurture, it comes for us all!) Now almost entirely fungus, bloaters—if in drier climates—or shamblers—if in wetter—have few, if any, human-like features apart from their bipedal movements.

Both bloaters and shamblers are clumsy, though they make up for their two left feet with profound aggression. They can rip a human apart with just their bare hands, should they manage to grab you. Their once-human skin has morphed into something puckered and indistinguishable, and their bodies provide them with an arsenal not available to runners, stalkers, or clickers. If you spot one, keep it zippy!

Bloaters are the tougher of the two: Characterized by their armored fungal plates and throwable mycotoxin sacs, you’ll need some significant firepower to break through to their vulnerable innards. (Thus why the bloater who pops up from underground in season 1, episode 5, seems virtually indestructible.) Shamblers, meanwhile, are easier to kill, but their acidic pustules burst whenever they sense a threat nearby. Getting too close to them isn’t an option, so you’ll want an army surplus store’s worth of ammunition on hand—or at least a dependable flamethrower. Either way, steer clear of both the bloaters’s toxins and the shamblers’s pustules. These acidic weapons can burn and infect your skin, so layer up if you’d prefer not to deal with one seriously disgusting rash.

Don’t ask how this bloater got so tall.

Stage 5(ish): The Rat King

This section contains some minor spoilers for the video game series, so breeze past if you’d prefer to sleep better at night.

In the game sequel, The Last of Us: Part II, there’s a technical fifth and final stage to the infection: a super-organism known as the Rat King. If, after multiple decades of infection and forced proximity, several infected hosts remain in the same area, it turns out that cordyceps is capable of weaving these hosts together, fusing them into one enormous mega-boss.

These symbiotic creatures are almost impossible to kill, given their advanced armor and speed. You’ll want not just guns but bombs to take them out, and even then the Rat King is still capable of splitting apart into individual stalkers, clickers, and bloaters.

The one comfort I can offer is that these creatures seem to be extremely rare. They require many, many years of contained infection without exterior interference. The Rat King in Part II, for instance, was made up of Seattle’s first patients, kept in quarantine once they were infected...and never allowed to leave.

Stage 6: Death

Infected do, eventually, die. They either succumb to injuries or of something akin to old age, as soon as the fungus has consumed enough of the human flesh. At this point, the host will find a spot hospitable to cordyceps—usually somewhere dark and moist—and grow still, becoming a corpse while the fungus itself continues to bloom. Over time, the dead body will turn into a sort of fungal blanket, spreading over walls and surfaces and filling entire buildings with spores. (In the TV show—which did away with the game’s spores for logistical reasons—tendrils are instead the resulting threat.) Only sunlight is capable of annihilating this corpse-fueled fungus entirely. If a light shines on the growth long enough, it will become bleached and hardened, then it will die. That’s an apt metaphor for a narrative like The Last of Us, steered by the Fireflies and their motto: “When you’re lost in the darkness, look for the light.”