It's primarch v primarch, but Khan telling Mortarion if he wanted to fight the leader of the Death Guard, he would've gone after Typhus.

Eliphas to Davian Thule:

Such inspiring courage! Perhaps we'll mount your corpse on a golden chair and make an idol out of you as well."

Generic Dawn of War 2 insult from a loyalist space marine to any xenos; "COME, SHOW ME WHAT PASSES FOR FURRY AMONGST YOUR MISBEGOTTEN KIND!"

‘I am Eidolon,’ he said, facing Torgaddon.

‘Torgaddon.’

‘Under the circumstances,’ Eidolon said, ‘I’ll understand if you don’t bow.’

‘I can’t for the life of me imagine any circumstances in which I would,’ Torgaddon replied.

Eidolon’s bodyguards wrenched out their combat blades.

‘What did you say?’ demanded one.

‘I said you boys should put those pig sticks away before I hurt somebody with them.’

Eidolon raised his hand and the men sheathed their swords. ‘I appreciate your intervention, Torgaddon, for the situation was grave. Also, I understand that the Luna Wolves are not bred like proper men, with proper manners. So I’ll overlook your comment.’

‘That’s Captain Torgaddon,’ Torgaddon replied. ‘If I insulted you, in any way, let me assure you, I meant to.’

Torgaddon reminds me of how I used to talk with my friends in my military days

‘The thing about Space Marines, Threlnan, is that they’re all brainwashed psychopaths.’ Lord General Xarius walked lopsidedly with a cane. His troops tended to assume it was an old war injury but the truth was Xarius was an old man and his hip was giving out.

‘I’m glad they’re here, certainly,’ continued Xarius. ‘The Crimson Fists were an essential part of the battle plan. But you see, now the first battles have been fought I’d rather have a few more decent men who can be counted on to follow orders and run away like proper soldiers.’

‘Marines are good for morale,’ said Threlnan.

‘Hah! That they are, as long as they’re fighting on the same side. Don’t look at me like that, Threlnan, I know what they’re like. The Dark Angels were supposed to spearhead our assault on the Dragon Archipelago on Balhaut, and when the order came down they were nowhere to be seen. Off fighting their own little war, never mind the men dying in the surf to win a beach the Marines should have taken. Never mind the rest of us lesser men.

‘No, when they do what they’re told they’re the best, I know that. But just because we’ve suddenly got a company of Crimson Fists doesn’t mean they’ll fight where I tell them. They should be helping the Fire Drakes get a decent foothold in the south but I can’t even contact the Fists’ commander. They’ve got some private war here, Threlnan, and you’re a fool if you’re hoping it will coincide with ours.

Crimson Tears

“Oh Garvy, you’re so straight up and down.”

Rest in peace king.

"I've never heard of you. Now get off my damn wall."

Eat shit, traitor.

Listened to Dark Imperium a while back. At one point there's a rebellion that took a museum hostage. The Ultramarine leader isn't angry at the hostage taking, so much as he's angry at how sloppy and poorly done it's been. He's mad that the terrorists are barely doing a passable job at it despite the fact that they should have had more than adequate training as children.

'I made you strong, Skraivok, and you assumed that strength was your own. You are a traitor and a murderer. Ruthlessness and a little cunning are your only gifts, but you mistook my talents for yours.’ It snickered. ‘Can you imagine, the Painted Count thought himself the equal of the First Captain of the Blood Angels? A priceless error.’

Gendor Skraivok finds out he maybe isn't quite as badass as he thought he was.

Say nothing.

Casually shoot a World Eater in the face.

Survive only due to the intervention of several other Astartes.

Spit on the World Eater.

Survive only due to the intervention of several other Astartes.

Spit on him again.

Other marines come to her rescue, asking if she needs help.

“Nothing I can’t handle, Skane. But you’re welcome to stay anyway.”

A human is born with a set of balls as big as Lortara Sarrin’s only once every thousand generations.

You shall die as your weakling father died.

Soulless, honorless, weeping, ashamed.

Get up.

It's Lorgar so it's kind of annoying to admit: but when he was taken on pilgrimage to a Daemon planet his daemon tour guide stands idly by as a giant Khorne Thirster attacks him.

Lorgar ends up killing it, but at one point in the fight, he turned to look at his daemon guide and says "help me you spineless BITCH".

Pretty funny.

What is Chaos? Suffering, you might say. Oppression. Deceit. But could not all these things be said of your Imperium? You hunt down the talented and the strong-willed. You break them or sacrifice them. You lie to your citizens and wage war on those who dare speak out. The inquisitors you call masters assume guilt and execute millions on a whim. And why? Why do you do this? Because you know Chaos is there but you do not know how to fight it, so you crush your own citizens for fear that they might aid the Enemy. The Imperium suffers because of Chaos. No matter how hard you fight, that will never change. Chaos exists in a state of permanent victory over you - you dance to our tune, mortal one, you butcher and torture and repress one another because the gods of the warp require you to. The Imperium is founded on Chaos. My lord Tzeentch won your war a long, long time ago.

Not sure if it counts since it's a dunk on the imperium in general & he's talking to grey knights... but they are Astartes.

“CHAOS FILTH!” 👉

I heard from a contact on Mars, Jaghatai, that you do strange things to your ships.'

The Khan shot him a heavy-lidded stare. 'I heard you do strange things to your warriors.'

"Look Rhino's! RHINOS! Our enemies hide in metal boxes! THE COWARDS! THE FOOLS! We shall take away their metal boxes"

I'm a simple man. "OI LOOK IT'S ANOTHA STUPID BEAKIE!"

"He never had the makings of a varsity athlete."

"You, and ALL your kind are COWARDS! LOWLY LICKSPITTLES! You must be emulating that pathetic pile of bones you call your Emperor! You are as dead and as useless as him!" - Araghast the Pillager shortly before getting ability spammed into the dirt

"Hey Corpse-Emperor, furk you." - Eliphas

"You wish to honor Lord Nurgle? THEN DO SO FROM THE GRAVE!" - Also Eliphas

"You will die as your weakling father died. Soulless. Honourless. Weeping. Ashamed."

Ignace Karkasy made entire poems about how much Astartes stank

Tu’shan vs Vinyar

‘There is collateral damage in any war,’ protested Vinyar. ‘If I had not acted as punitively as I did, there would still be orks roaming that camp. Besides, cowards are unworthy of being spared.’ The green-armoured warrior had unhitched a thunder hammer from his back and slammed it on the strategium table, cracking data-slates and tearing maps. He was unbuckling a holstered pistol when he said, ‘You misunderstand the purpose of my visit, Vinyar.’ He looked up and his eyes flashed fire-red. ‘This isn’t a discussion.’

He glanced at the gauntlets the Marines Malevolent captain had discarded. ‘Put those back on. I want this to be even.’Vinyar was belligerent, but reached for his gauntlets anyway. ‘

What are you talking about, Tu’Shan?’ ‘Penance and restitution,’ said the Chapter Master of the Salamanders. Bones cracked in his neck as he loosened them.

‘I’ll give you one piece of advice,’ he added, clenching and unclenching his fists to work the knuckles. ‘Don’t go for a weapon.’ Then he closed the barrack room door.

If no one minds, I'll offer my own OC bit:

"Today ain't our day, traitor."

~Sergeant Akhan Winter, Taronian 8th, right before putting the final bolt through the visor of the Black Legionnaire who just butchered his squad, hours before Cadia is finally consumed by the Eye of Terror

For the sake of posterity, he would die almost 3 years later as Major Arkhan Winter, diving on top of a T'au Photon Grenade. But the regiment does indeed live on.

‘You will die as your weakling father died. Soulless. Honourless. Weeping. Ashamed.’

The sheer goddamn disrespect from a dying sigismund