A short moment after the game starts, you will get a short premonition of the monster in the current round. Do note that this premonition can appear after the monster is already out.

Description:
A nosferatu-like monster with elongated limbs

Traits:
Physical - It physically exists, thus it will not disappear or teleport. They can be locked in the maintenance room by baiting them into the maintenance room and removing the power source.
Hearing - It can hear noises such as the opening of doors and speaking through mics. Crouch walk/don't run with the ghoul around.
Blind - It cannot see anything so if you stay quiet and stay far from the
Metal Noises - They can be identified by the metallic noises when they walk around.

Attack:
The blind ghoul attacks through contact. Once they come in contact with a human, they will start an attack animation which will leave the victim downed. The process can be interrupted by a single blast of the fog horn. If you stun it after the kill animation proceeds past a certain point, the victim will still be downed but the ghoul will be stunned.

Weakness:
Foghorn - The foghorn can be used to stun the blind ghoul repeatedly. You do not need the full blast, so after you hear the blast and see the ghoul reeling, stop and wait for the next blast, just keep blasting and the ghoul can be stunlocked.
Tranquilizer Gun - Tranquilizer darts fired from tranquilizer guns can apparently slow the ghoul down.

Note:
For items that are hidden within display cases and other containers which will cause noise, interact and hide quickly. Wait until the ghoul is done investigating and then proceed. They can also open lever gates.

Description:
Stone stalkers look like marble statues of women.
If you've ever watched Dr. Who, they are basically weeping angels.

Traits:
Physical - It physically exists, thus it will not disappear or teleport. They can be locked in the maintenance room by baiting them into the maintenance room and removing the power source.
Move when unseen - They can only move when they are not within sight of humans. They move at a decently fast speed. You can hear their movement in the form of a stone scraping noise.

Attack:
By contact - They down humans that they come in contact with a grabbing attack.

Weakness:
Visual contact - If possible, lure all the statues (maximum I've seen is 5) into an area and have one player be able to keep eyes on all of them so the rest can proceed. They can be temporarily disabled by dropping gates on them.

Description:
A black shadow humanoid tree-monster with glowing eyes

Traits:
Ethereal - It isn't physically present, and can thus disappear and teleport around.

Attack:
Will manifest then walk towards and grab humans to attack when it comes into contact.
Upon 3 fuses being active, they will become faster and will no longer have a cooldown after killing someone.

Weakness:
Camera Flash - Can be temporarily dispelled with the camera's flash.
Hiding spots - Hiding under tables and wait for the hidebehind to leave can work

Note:
Sometimes it will disappear when looked at. Not sure if it is a weakness. There has also been unconfirmed reports of the Hidebehind will disappear if you turn your back on it when it appears before starting to move for the kill.

Description:
A blue ghost lady.

Traits:
Ethereal - It isn't physically present, and can thus disappear and teleport around.
Singing - She will sing when she is idle. If you hear otherworldly singing, the monster is the banshee.

Attacks:
The banshee will wail and freeze everyone in the vicinity. They will then approach the nearest victim and start a grab attack.
Upon 3 fuses being active, they will gain a dash attack where they will dash in a straight line, downing people caught in the attack.

Weakness:
Earmuffs - Earmuffs will make you impervious to her wails, thus you won't be frozen even if you are around the banshee when she is wailing. However, if you physically touch her, you will still trigger her attack animation and get downed.
Camera Flash - Can be temporarily dispelled with the camera's flash.
Metallic objects - They do not like metallic objects. They can be dispelled with a metallic item such as the crowbar being thrown at them. Big shout-out to the developer for providing this.

Note:
They can sometimes move through walls and kill people in rooms.
People frozen by the banshee, assuming they are not attacked and downed immediately, can be warmed up either manually or with a hairdryer.