Played with in Warhammer 40,000 - that guy in the black armour with the skull mask screaming out litanies of hatred ("SUFFER NOT THE UNCLEAN TO LIVE!") against everybody else than him and everybody on his side? He's a Space Marine chaplain - and arguably one of the setting's ambiguously 'good' guys. Then there's the Space Marine chapters with names like Flesh Tearers and Soul Drinkers. That scar-faced woman with a cybernetic arm riding into combat against civilians on a tank adorned with spikes, crushing them under her wheels while incinerating them with hi-tec flame throwers? Also arguably relatively good.
The oddities of naming conventions are discussed hilariously here.
The Troperiffic setting has plenty of straight examples as well, such as giant all-consuming psychic insects and invincible undead robotic servants of star-eating Eldritch Abominations. Then there's Chaos Space Marines, the poster boys of this trope. Their armour tends to be covered with skulls (they like trophies) spikes, horns, and the occasional pieces of flayed human skin and they worship dark gods and summon daemons. While some (like the Khorne Berserkers) might leave helpless civilians alone (as they want a Worthy Opponent), most just tend to slaughter everybody in their way in order to raise their standing in the eyes of the Chaos Gods or just because they like to rape and murder.
A Khorne Berserker not killing people? KHORNE DOES NOT CARE FROM WHOM THE BLOOD FLOWS, ONLY THAT IT FLOWS
And then there's the Orks, who are big, green, brutish, warlike, loving-to-fight, lots of horns, guns, horrible to each other (and especially Gretchins)... who just want a good fight and will actually leave a planet if they don't put up a good enough fight, or they've killed everyone who can, so they can come back and fight again. As they say, Orkz wuz made forfoitin' an' winnin'!. One could actually argue that the Orks are the least evil of all of the factions.
There are some heroes — look at Ibram Gaunt, a humane badass. Who dresses in a pseudo-Nazi uniform decorated with skulls.
It is very tricky applying this to the verse because of the sheer level of Alternative Character Interpretation and Unreliable Narrators. The three factions that can in no sense be considered even halfway sympathetic, however, fit this trope like above. Besides the bugs, robots and Super Soldier destroyers and their wiping-planets-completely-free-of-life antics, we have the Dark Eldar, with black, spike-covered equipment and units named after demons. Torture and treachery are their favorite pastimes. They eat souls. Their actions created an Eldritch Abomination of Squick that wiped out most of their race, and they kept on with business as usual.
An argument can actually be made for the Tyranids not being Evil. They certainly aren't *good* but their Blue and Orange Morality combined with a natural need to feed makes them no more evil than a swarm of the space locusts they are, or ants. Nobody likes seeing an ant kill a butterfly, but the ant's lack of empathy being biological kindof prevents the action from being evil explicitly.
Most demons in Dungeons & Dragons. Consider Orcus, the Demon Prince of the Undead, who is a gigantic, bat-winged, goat-headed, grotesquely obese monstrosity who carries a wand with a skull on top. Yeah, trustworthy, that guy.
The Coalition States in Rifts is The Imperium of Man Lite version; a collection of xenophobic humans with aggressive intentions, a hatred of anything non-human or magic-using, with armies of fanatical soldiers, genetically engineered dog-men and robot soldiers for the purpose of reconquering North America. Oh, and all their armors, ships and robots have a "death's head" skull motif for decoration, earning them the nickname "Deadboys".