Off the top of my head, the Bible really says surprisingly little about demons, and various translations will say even less (depending on if the translator thinks an evil spirit=demon or not). Generally, the possessed act either mentally or physically ill, or they get scared of Jesus. Beelzebub is the prince of demons, but that's about all we know from accepted scripture. Most "Christian" demonology stems from writings that didn't make the final cut for the Bible, mythology borrowed from other cultures/religion, bored/crazy monks in a position to write things down, and particularly influential works that never claimed to be anything but fiction (namely Dante's Inferno).

Surprisingly, a lot of the creepy media is fairly accurate, though extreme. Demons aren't prominent, we know they are angels who rebelled with Lucifer, and were cast out, so that would be their appearance, but in reference to possession, we basically have those that Jesus encountered and a few his apostles drove out in his name later on.

And what we see are people behaving almost like animals, screaming, shouting, with an inhuman strength to break chains or whatever locals have tried to contain them with, and inflicting a lot of self harm. There's a woman who would throw herself into fires, a man who had 100 demons in him (where "I am legion" comes from") who would throw himself onto rocks and off cliffs and cut himself, etc.

The more manufactured elements are the head twisting, anything to do with pentagrams, and honestly a lot of the hostility to others. People usually steered clear, but demon possessed individuals generally did more self harm than harming others, with cases where Jesus would meet them within cities, and they weren't surrounded by dead people or a panicking mob or anything. They also don't "haunt" or hunt people like they do in movies, but are usually extremely obvious.

Anyway, that's my experience purely from biblical account, off the top of my head, I'm sure others can add more detail or examples.

There really isn't any until the exorcisms of the NT, which is again missing much description.

Even the parts that some people think are describing demons often aren't.

For example, the locusts of Revelations:

And the fifth angel blew his trumpet, and I saw a star that had fallen from heaven to earth, and he was given the key to the shaft of the bottomless pit; he opened the shaft of the bottomless pit, and from the shaft rose smoke like the smoke of a great furnace, and the sun and the air were darkened with the smoke from the shaft. Then from the smoke came locusts on the earth, and they were given authority like the authority of scorpions of the earth. They were told not to damage the grass of the earth or any green growth or any tree, but only those people who do not have the seal of God on their foreheads. They were allowed to torment them for five months but not to kill them, and the agony suffered was like that caused by a scorpion when it stings someone. And in those days people will seek death but will not find it; they will long to die, but death will flee from them.

In appearance the locusts were like horses equipped for battle. On their heads were what looked like crowns of gold; their faces were like human faces, their hair like women’s hair, and their teeth like lions’ teeth; they had scales like iron breastplates, and the noise of their wings was like the noise of many chariots with horses rushing into battle. They have tails like scorpions, with stingers, and in their tails is their power to harm people for five months. They have as king over them the angel of the bottomless pit; his name in Hebrew is Abaddon, and in Greek he is called Apollyon.

Look closely at a few of the details there:

• allowed to torment for five months
• the agony suffered was like that caused by a scorpion when it stings someone
• like horses equipped for battle
• On their heads were what looked like crowns of gold
• faces were like human faces
• hair like women’s hair
• their teeth like lions’ teeth
• scales like iron breastplates
• the noise of their wings was like the noise of many chariots
• tails like scorpions, with stingers
• in their tails is their power to harm people for five months
• have as king over them

So back in the day, there was no Greek word for a specific hornet, just a general term that applied to any wasps.

But in Judea the equivalent of the murder hornet was Vespa Orientalis.

This hornet, like many wasps, was active outside its nest for 5 months.

At the time, they thought a hive was ruled by a king, not a queen (thanks a lot Aristotle). And their nests are made underground (like the pit in the passage above).

Like most hornets, they had mandibles with large 'teeth' like a lion.

Unlike locusts, their faces were more human looking with the placement of the eyes centrally as opposed to on the edges of the head.

They were covered in fine hairs like a woman's body hair.

Covered in segmented 'scales' with stings painful like a scorpion.

They had a yellow stripe across the lower part like a saddle (this was actually used to effectively solar power the insect).

But the most striking similarity between the above passage and this specific insect native to the area was the gold crown marker on its head: https://www.biolib.cz/IMG/GAL/33881.jpg

So while people have had their imaginations running wild with Fabio looking scorpion/horse chimeras for years now, it may have simply been a poetic description of the local murder hornet equivalent being really active and stinging people - a nightmarish scenario for anyone who has been on the wrong end of a hornet before, but not quite the nightmarish people have been dreaming up since.

So I recently listened to an episode of the Data over Dogma podcast specifically regarding angels and demons. It’s hosted by Dan Beecher (an atheist podcaster) and Dr. Dan McClellan (a Bible scholar), and they discuss how angels and demons are actually depicted/described in the Bible, compared to the extra-biblical descriptions of both that we’ve gotten over the millennia. It’s about an hour but should serve as a nice little primer on the subject, with some recommendations for further study.

I’ve only gotten to Leviticus in my Bible reading. God that chapter is a slog.

Anyway, if you need to know which part of the goat may be a waved offering and which may be a burnt offering and which may be a meat offering, and which order in which to pile the guts and the cauls and the livers and hearts and bones thereof and all the fat within and all the viscera and connective tissue so that the priest may toss three splashes of blood on the left side and three splashes of blood to the right side and so on and so forth, I might be able to help.

I guess one positive thing about slogging through Leviticus is I now realize how many ways there are to sacrifice a goat.

Biblically, demons are simply fallen angels.

Metatron has done a video on this ( https://youtu.be/-Mx6TtkgugU?si=7SS7s9JpMupmmpKl ). I don't think he's religious, but he knows his stuff when it comes to classical history. I haven't watched this video in a while, but I think it's more about the demons in the Bible that are close to modern pop culture demons (horns, big bat wings, etc), rather than the sorts of demons that actually possess people.

If you're asking what Christians think demonic possession is like today, it's far more subtle than it is in the Bible. The goal of any demon is to lead people away from God, so openly showing themselves to a secular culture that believes they're fake is unhelpful. All of the stories I've heard of demonic activity have been where three demons imitate actual medical conditions like asthma, migranes, or epilepsy. The way to tell between purely medical conditions and demonic activity is with prayer and God helping you discern what it is. The only tell apart from this would be doctors doing everything they can and the problem only getting worse.

If you want to know more about demons, I recommend the Screwtape letters by C.S. Lewis.

Just watched Exorcist 3 last night. Great timing. Sorry that I have nothing to add (atm).

In the bible, the demons are fallen angels so....

Most of the lore you see is from dantes inferno, not the bible.

I watched this about it recently. Enjoy

https://youtu.be/-Mx6TtkgugU?si=GIgFG5R0REwusvHF