One of the greatest bullets in Doom's arsenal is its great variety of demons and monstrous entities. These are some of the most strategic and intelligent demons in how they attack. They are not all especially powerful, but given the opportunity they can be very effective. Sometimes they do not work very well when grouped up in clusters, but in wide open trios, they can kill if they all attack at once.
The demons on this list have stood the test of time and have been given some amazing reiterations through gaming history. You may have to use the BFG 9000 more than once on some of these horrors. However, it is the hardest shell to crack that makes ripping and tearing so satisfying. These are demons that are not only powerful, but also iconic in more ways than one.
The Archvile
We're going to be honest with ourselves and admit that no one actually likes to see this demon show up. They have a devastating fire attack that hits you hard and from a great distance and they can tank three rockets to the face. You have to get out of their line of sight and then use launcher or plasma gun at a distance, the Super Shotgun up close. They are priority targets, but we also have to admit that they have had a very positive effect. Not only do they look awesome, but the way they resurrect other creatures and give you the adrenaline rush just speaks volumes.
Imp
Running into human zombie creatures in the first level was one thing, but then running into these weird spiked creatures happened. They start throwing fireballs at you, you're not entirely sure how to handle this and that is a fantastic introduction to Doom! The imp is in every iteration of Doom and there is a very good reason for this. When mixed with other monsters, their fireballs can come out of nowhere. Imps can populate a map and be taken out with explosives, but normally the shotgun works just fine. They aren't all that strong, but they'll kill you with a thousand cuts!
Mancubus
These huge, massive tiger-striped aliens were very iconic of Doom 2. The Archvile was an occasional appearance but the Mancubus was used quite a bit to glorious effect! Their fire attacks can be dodged but they are devastating to your health! These big bastards also absorb a lot of bullets and their death animations are awesome, no matter what Doom game you're playing! The original classic iterations also had some very unique soundclips to them. Of all the beasts, they strangely sound the most human.
Revenant
These are skeletons. That's all. Do not pay attention to the fact that they have missile launchers on their shoulders and some of them are heatseeking missiles! These guys take a bit more to take down than your normal affair, but they can also slap you rather hard from a long distance. Make sure the missiles bank onto a wall and explode because you need to dodge quick! Don't even get into the fact that they start flying in Doom 4!
Demon (Pinky)
So, you've had a few levels of human things and imps, so you think you know Doom. That's when they start throwing these weird, pink demons at you that start to gnaw! These were just "demons" in the original lineup, but thanks to fanfare and love for this little guy, it has now been named "Pinky". The Pinkies even get a front armor upgrade in Doom 4 and their charges become even harder hitting! They make up for it with a soft backside and a fang that you can slide across its throat!
Cacodemon
When you think iconic demon, you start to see flying faces with one eye! These big red spheres shoot lightning fireballs, if that makes any sense, and they are obviously a bit more complex to deal with when there are ground-crawling horde demons nipping at your heels. They can be taken care of with a chaingun rather well, as they get the hurt face, which is their body!
Spider Mastermind
The arachnotron was going to make the list, but the Spider Mastermind has to take the iconic role on this particular list in the Doomverse! Every shot from his chaingun has the impact of a shotgun and he is a bullet sponge! Now, is he as much of a challenge to be his own boss battle? No, not so much. While he may have been a bit of a disappointment when you bear a full arsenal, he has his place among the greats with his part in other levels. His fight in the Doom 2 level, "Gotcha", can always be marvelled at. It's fun to see that he can either win or lose the fight. Although, the problem is that the next demon usually wins.
Cyberdemon
These big bastards started with Ultimate Doom and they are not to be trifled with. In the first level you meet him, he is accompanied by Lost Souls. If you know Doom, you know using the rocket launcher against Lost Souls can be a big mistake. So, obviously, save up all of your cell charges and use the BFG and the plasmarifle as needed. When those fail, the chaingun at a distance or the Super Shotgun up close. The Cyberdemon is immune to rocket area damage, so keep out of his way.
The Bruiser Brothers
When you played Knee Deep in the Dead, the last two demons you met were two Barons of Hell. The Bruiser Brothers were coined and they attacked you along with some spectres in the arena. Their green flame attacks are critically damaging, but they also are easy to read. Circle strafing them with a rocket launcher and a chaingun will do the trick. Obviously, if you haven't noticed, the Super Shotgun works in many of these situations as well. Sadly, if you're playing the straight first game, then the Super Shotgun wasn't a weapon yet. However effective it is against Barons. Though, it's not so much for the last on our list.
The Icon of Sin
Love it or hate it, The Icon of Sin is literally an icon! In order to hurt this thing, you need to shoot the brain with either the BFG or the rocket launcher. You have to do partial area damage to the "brain" in order to destroy it. The demon spawning Doom 2 final villain is not so well looked upon by many, but behind that visage of the demon, there is another icon. Not only has John Romero been the "brain" put behind it with his head on a peg, his voice also accompanies the level, backwards. This, by default, makes this villain awesome. Not only that, but they brought him back for Doom Eternal and gave him an awesome boss battle. He has more than earned his place on the top of this list.
