Former Soldier
"Once a marine or guard like the protagonist, now a green-haired, Hell-possessed soldier carrying a rifle. The weakest of the enemies in Doom and therefore, the easiest to kill." (Doom Wiki)
These bastards use hitscan weaponry in the game, and so in the Pathfinder 2e variant they have an extremely high To-Hit bonus for their level but deal fairly low damage, allowing them to pepper you with shots from across the battlefield and needing you to rush to take them down (and they drop fairly easily with their low AC and health) before they slowly deplete all of your health
Former Soldier CREATURE 1
rifle +11 (deadly d8, range increment 120 feet, reload 0) 1d4+2 piercing
Imp
"A brown, human-sized humanoid demon that throws round fireballs and claws nearby opponents." (Doom Wiki)
These lads shoot a large quantity of slow moving projectiles towards you, but fall in only a few shots so they aren't too big of a threat. However, they've got a nasty claw attack if you get too close to them.
Imp CREATURE 2
claw +9 (agile) 1d8+4 slashing fireball +7 (range increment 60 feet, reload 0) 1d10+4 fire plus 1 splash fire
Former Sergeant
"A bald, more durable zombie in black armor with a shotgun. A bit tougher than the Zombieman (perhaps due to his rank), but still very easy to gun down." (Doom Wiki)
Another hitscanner from the games, and even more annoying because they can chunk you down much faster than the Former Soldier while also being harder to kill. Generally the #1 priority target.
Former Sergeant CREATURE 2
shotgun +11 (deadly d6, range increment 30 feet, reload 1)1d6+3 piercing plus buckshot
Pinky
"About the size of a gorilla, this muscular pink brute runs quickly on its two hind legs to bite opponents. While not an immediate threat on their own, when in groups they do have a tendency to try and outflank their targets." (Doom Wiki)
These creatures charge you down and then just keep biting you until you either die or kill it. That's basically it. They are no threat at a range, but once they get close you are in for a world of hurt.
Pinky CREATURE 2
bite +91d8+4 piercing
The pinky Strides twice, then makes a bite Strike. If it moved at least 20 feet from its starting position, the Strike’s damage is increased to 2d8+6. bite
Spectre
"Identical to the Demon (Pinky), except that it is partially invisible." (Doom Wiki)
Yep, that quote basically says it all.
Spectre CREATURE 3
bite +91d12+4 piercing The spectre Strides twice, then makes a bite Strike. If it moved at least 20 feet from its starting position, the Strike’s damage is increased to 2d8+6. bite
Baron of Hell
"Two of these act as the boss in Knee-Deep in the Dead, resembling large blood red Satyrs. It can hurl streaming balls of green plasma and employs a powerful clawing attack at close range. They can take enormous punishment before being slain." (Doom Wiki)
These towering beasts can rip you a new one if you get too close to them, but even at a range they can deal some heavy damage by flinging green plasma at you. The only good news for you is that they are a bit slow, but you'll probably die too fast to notice.
Baron of Hell CREATURE 5
claw +132d12+7 bludgeoning plasma ball +15 (range increment 60 feet, reload 0)2d8+7 fire
The baron makes a melee Strike. This counts as two attacks when calculating the baron's multiple attack penalty. If this Strike hits, the baron deals an extra die of weapon damage. (auditory, concentrate, emotion, mental); The baron rolls for initiative Bellowing mightily, the baron gives themself and all demon allies within 60 feet a +1 status bonus to attack and damage rolls until the end of the first round.
Cacodemon
"A large flying head-like monster with red scales, horns, and one eye. It moves relatively slowly, but has strong jaws and spits out "lightning balls" from a distance." (Doom Wiki)
These creatures can chunk down your hit points fast if you don't keep an eye on them, but if you are able to keep damaging them every round then they can consistently be slowed to become nearly useless.
Cacodemon CREATURE 4
jaws +122d10+7 piercing lightning ball +9 (range increment 60 feet, reload 0)2d8+5 electricity
Cyberdemon
"The massive boss in The Shores of Hell, a monstrous humanoid cyborg as tall as two men that can absorb more damage than any other monster and moves at a relatively rapid rate for its size, pausing only to fire rockets from its mechanical arm at anything foolish enough to oppose it." (Doom Wiki)
You arrive at the final section of the demonic citadel, and find four barons of hell crucified on the walls around you. What sort of monster could kill that many of those monstrosities? You soon learn, as you see the skyscraper of machinery and flesh, towering over you with it’s rocket launcher arm pointed right at you. This is the cyberdemon.
Cyberdemon CREATURE 8
stomp +222d12+15 bludgeoning rocket +18 (range increment 60 feet, reload 0)2d10+11 fire plus 5 splash piercing
(auditory, concentrate, emotion, mental); The cyberdemon rolls for initiative Bellowing mightily, the cyberdemon gives themself and all demon allies within 60 feet a +2 status bonus to attack and damage rolls until the end of the first round. The cyberdemon makes three rocket attacks. Apply its multi attack penalty to each Strike normally.
All art and original monster ideas from the ID Software team and from DOOM (1993), I'm just making pathfinder 2e statblocks for them.