Of the type often seen in movies where the body is rotten, no. Dead tissue doesn’t move.

However, there are approximations:

For starters there’s a type of fungus that hijacks ants, using it to spread its spores into other ants. It can control the ants movement to the point where it will cause the and to go to certain good spore-spread8ng places before the ant is devoured.

Then there’s the disease that affects raindeer in some places. I don’t remember the illness, but basically the mind goes byebye while the body is left to be controlled by less and less sophisticated parts of the brain, to the point where the animal can do nothing but walk in circles.

Undead Zombies? No. I’m no virologist, but I’ve read about a Rabies variety, or certain fungal infections. Fiction-wise, World War Z, or 28 Days type “zombies”, where the body is very much functioning, but the brain has been hijacked…

the type for brain hijacking definately, as theres a fungus that brainhijacks ants.

the type that that works on dead people, likely not. all viruses and stuff survive by trying to keep their host alive. the ones that kill their host die off quick.

By definition? No. Don’t listen to any of these, “exceptions.” You asked a direct question and the direct answer is no.

We call them Republicans here in the US

Yes but in a different way than literal. Zombie movies tap into a fear of a real-life monster called The Mob. When people become part of a Mob, they lose their humanity, and will destroy you mindlessly.

Like, if you see an angry mob coming your way, you need to treat it like a zombie situation. And the instinctual, evolved fear of that mob is exactly what zombie movies evoke in us.

I’ve seen a living zombie hoard before, at a dump in Nicaragua where they lived. I was told they got high on sniffing shoe glue, which literally causes the brain to decay while they’re still “alive,” but they just shambled around in a big mob, seemingly aimlessly, with glue smeared under their noses.

No, until yes.

Atypical rabies I would say would be pretty close. Good thing rabies is pretty rare.

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Which version? If all you need is an uncoordinated, dopey person, I’m right here. /s

If undeath is required, no. It’s not even a concept that makes much sense without mind-body dualism, which is all but ruled out scientifically.

The closest that I know of that’s known and possible is with a fungus. Possibly a parasite, but probably fungal.

Some parasites, especially those that infect insects, can cause the host to go crazy, for lack of a better word, and “infect” others through bodily fluid transfer. Fungal is similar; IMO, fungal would be my guess since to me, given how large fungal networks and organisms can be, it would be the most likely candidate to adapt to the size and scale required to control a human.

However, it is unlikely. There’s a pretty slim margin between being infectious enough to be viable and so infectious the host dies before there can be any useful progression of the disease. It’s just a very fine line.

Depending on what version of zombies you’re thinking of, it may be more, or less zombie-like. In the case of the walking dead? No. Not really possible. Maybe in a million years, caused by nano scale machines, where the machines more or less use your corpse as meat armor… But that’s a very long way from becoming a reality. The "real zombies would be more like possessed living people, still vulnerable to the same dangers as other living humans. If you shoot them, they will die. They wouldn’t be super strong, maybe mildly more strong than they were when they were living, simply based on the fact that we tend to hold ourselves back a bit when it comes to our strength because we want to avoid damaging ourselves too much during the effort… “Zombies” wouldn’t have those concerns so they may be stronger, but not so significantly that it would matter all that much.

Skin appearance may be affected due to the infection and may cause the flesh to appear sticky.

Since most higher brain functions would be suppressed, tactics and planning would not be possible, or at least, extremely limited, and most advanced skills would also be unavailable (working tools or machinery). There would also be very little in terms of language skills, if any.

Since the infected would have the primary goal of spreading the infection, they likely wouldn’t eat or sustain themselves in any meaningful way, leading to death in a matter of days, maybe a week or so, at most. Zombies would probably smell of human excrement, since the infected wouldn’t be concerned about where they relieve themselves and likely just piss or shit right in their pants as the need arises.

TL:DR: they would be far shorter lived and far less dangerous than seen on TV but it’s possible that a parasite or fungus could invoke such tenancies

If this stuff sarts infecting humans yes. .

As with other versions, it’s not impossible but the zombie is unlikely to he viable more than a couple weeks, as decomposition doesn’t stop.

Yes, but not quite like the movies.

There is a parasite (I forget the name) that, when it infects a person (or a warm-blooded animal) starts living off the host and storing energy in sacs around the infection point. It often presents itself as tumours, as the sacs can get quite large. Between the sacs there is a voltage difference, it’s stored as chemical energy (like a battery with one side less electrons to allow for electron flow).

In severe cases, the parasite has had long enough to grow it’s own nerve pathways through the body that can be used like wires. At that point, the tumours are really advanced and enlarged and will usually kill the victim, if not before.

In an effort to spread itself to the next host, the parasite uses the stored chemical energy to activate muscles in the dead host and move the body around to find another host to infect. That’s where the whole ‘eating flesh’ thing in the movies come from, but it’s actually the parasite trying to break the skin and be able to jump to a new victim.

In reality, this stage only lasts a few hours but as long as the muscles haven’t deteriorated too much, it can be any ‘few hours’ movement within a couple days of death if the parasite is unable to immediately reinfect and instead waits for a period of time.

If we set aside Hollywood for a moment to talk about something unexpected… this is a completely serious and rather interesting subject of study:

https://en.wikipedia.org/wiki/Philosophical_zombie

My position on the matter is that it is quite easy to design systems that are to some degree “intelligent” (for most definitions of intelligence), without possessing qualia (consciousness, subjective experience). Several such systems exist, and you have probably heard of them!

Moreover, I think many natural persons can be intelligent without being conscious, at least sometimes. I think many people have this experience when working on difficult problems, e.g. programming.

For Hollywood-style zombies? I would start with chemistry rather than biology. There are many substances that can alter our mood, body control, aggression, and consciousness. Find a mix that creates the effect you want, and create an implant (or make it an addictive drug mixture). Probably the result would be less consistent than hollywood-style zombies. It would not be contagious though.

Or if sci-fi, insert genes into a living person that encodes a system to internally synthesize the drug mix.

Edit: Something that makes most people into shuffling drones? Increases aggression? Spreads like a disease? A cynical answer would be that we have invented that already. We call it “capital”.