Demons are inter-dimensional beings who travel from world to world and destroy everything in their path. They return to their dimension when they die. There are many different kinds of Demons. Most Demons are poisonous and the Nephilim healing rune (the iratze) is ineffective against it.

If you don't know what you want your demon to be like here's a list of the types of minor demons found in the Mortal Instruments books!

Lesser Demons:

Ahiab Demon - A massive scaled demon with a thick, lizard-like body. It's blind and has a keen sense of smell. A thick line of serrated teeth run along its forehead where eyes should be. It has another mouth on the lower half of its face as well, fanged with dripping tusks. It has a narrow tail that glitters as it moves due to it being edged with razor-sharp lines of bone. It has talons and a long, forked tongue with a bulb at the end of it like a scorpion's stinger. It rapes his victims before killing them.

Behemoth Demon - It is formless, huge and slimy. A double row of teeth runs along the length of its oblong body. It slithers with an oozing, boneless motion. It eats anything and everything - people included. It can teleport and its mucus turns seraph blades ineffective. It is semi-corporal and very hard to kill. It can heal its wounds but it seeps its energy - the best way to kill it is to keep wounding it until it can no longer heal itself. Clarissa Fray describes it as "a blind slug with teeth". It creates low noises like angry insectile chittering when angered and when it is killed it leaves behind a puddle of steaming green fluid.

Croucher Demon - Its poison is not life-endangering.

Drevak Demon - It is blind and tracks by smell. They smell rotten, like garbage and are incredibly fast. This demon is not a figher, it is mainly used as a spy or a messenger (implying it is capable of human speech). It does not suck its victim's blood. Drevak demons don't have teeth, they have poisonous black spines in their mouths. Drevak poison is incredibly painful and poisonous and should be dealt with by a warlock. A Devrak attack is called a "Devrak sting".

Eidolon Demon - it has the ability to shape-shift.
Hydra Demon - Has several heads,hard to kill and usually used a sort of guard dog

Iblis Demon - human-shaped but formed of a substance like coiling black smoke and a pair of burning yellow eyes. It likes to surround its prey but is not very bright. It bursts into ash when it dies.

Kuri Demon - Slinking and black.

Moloch Demon - likes to fight in groups. It has claws and jets flame from its empty eyes.

Oni Demon - has a green body, wide mouth, and horns (sharp tusks sprouting from its forehead). It has legs like tree branches and spade-like hands. It is smart.

Raum Demon - Dead white with scaled skin, a black hole for a mouth, bulging toad-like eyes, and arms that end in tentacles where hands should be. The tentacles are grey-white and tipped with blood-red suckers. Inside each sucker is a cluster of needle-sharp teeth. It has black blood and is poisonous. It is more dangerous than a Devrak demon and is incredibly fast.

Ravener Demon - A long, scaled demon with a cluster of eyes set dead center in the front of its domed skull. It is something like a cross between an Alligator and a centipede with a thick flat snout and a barbed tail that whips from side to side. It has multiple legs and claws as well as a row of fanged teeth. He drools green fluid and is extremely slimy and poisonous. It can hang off of walls and has a long black tongue.

Scorprios Demon - has a wrinkled face, the agile hands of a huge monkey but the long, barbed tail of a scorpion. Its eyes are rolling and yellow and it has teeth like broken needles. It hisses. It is incredibly fast and very poisonous. It uses its scorpion-like tail as a weapon.

Shax Demon - has pincers and an insect-like carapce. They are brood parasites, who bring their victims back to their lairs in order to lay eggs in them while they are still alive. They also have a sharp sense of smell, and can be used for tracking.

Spider Demon - has eight pincer-tipped arms and poison-dripping fangs that protrude from its eye sockets. It sprays acidic poison.

Unidentified Demons:

Unknown Demon 1 - looks like a huge, awkward bird. An ugly, flying thing that resembles a pterodactyl with wide leathery wings and a bony triangular head. Its mouth is full of serrated shark teeth, row upon row of them, and its claws glint like straight razors. It has no eyes, only indentations on each side of its skull. The wings end in blade-sharp ridges of bone. It bursts apart when it dies, leaving a wisp of black smoke behind.

Unknown Demon 2 - huge, humped and massive. Five times the size of other demons, it has an armoured body, many limbs, and each appendage ends in a spiked chitinous talon. It has elephant feet, huge and splayed. It has the head of a giant mosquito, complete with insectile eyes and a dangling blood-red feeding tube. It screams like a human and is very, very strong.

Unknown Demon 3 - An animated skeleton that fights with a bloody hatchet clutched in a bony hand.

Unknown Demon 4 - lizard-looking with rodent teeth and black claws.