We all love a goblin or ogrillon, and don't get me started on gnolls. But these days I increasingly wonder what function evil humanoids really have in a game. Humans can be evil and scary enough.
For example, I provide you with a link to a recent Sam Harris podcast on the proviso that once heard, some things cannot be unheard: https://samharris.org/podcasts/213-worst-epidemic/. (I hesitate to do so, but feel that this sort of thing needs to be known so we can somehow guard against it; needless to say, if ever there ought to be a trigger warning, consider this to be it. Don't listen to it if there is any indication the contents will upset you, because they will.) If you ever needed convincing that humans are capable of much worse than even the evilest of orcs, then you will be convinced by that. Others of you may prefer to look up the exploits of Fred West, Oskar Dirlewanger, or any of the other thousands of names in that infamous roll call of psychopaths and sadists which has plagued mankind since we split off from the chimpanzees.
The ancients understood good and evil, because they lived in a world in which evil was inescapable. (I'm reminded of Romeo Dallaire's comment: "After one of my many presentations following my return from Rwanda, a Canadian Forces padre asked me how, after all I had seen and experienced, I could still believe in God. I answered that I know there is a God because in Rwanda I shook hands with the devil. I have seen him, I have smelled him and I have touched him. I know the devil exists, and therefore I know there is a God.") It was all around them and they knew it intimately. No goblins or orcs, there. Just each other.
I recently finished reading Flaubert's Salammbo. Here are some extracts:
But a cry, an appalling cry broke out, a roar of pain and anger; it was the seventy-two elephants rushing in a double line, Hamilcar having waited for the Mercenaries to be concentrated in one place before loosing them; the Indians had goaded them so vigorously that blood flowed over their great ears. Their trunks, daubed with red lead, stood up straight in the air, like red serpents; a spear was fitted on their chests, their backs were armoured, their tusks extended by curved steel blades like sabres - and to make them fiercer they had been made drunk with a mixture of pepper, neat wine, and incense. They shook their collars full of little bells, trumpeted; and their drivers bent their heads beneath the shower of fire-arrows which began to rain from the towers.
The Barbarians rushed into a compact mass to offer better resistance; the elephants charged into the midst of them. The spurs on their chests, like the prow of a ship, tore through the cohorts, which flowed back in great waves. They choked men with their trunks, or tore them from the ground and delivered them to the soldiers in the towers; they used their tusks to disembowel them, and threw them up in the air, so that long entrails hung around their ivory teeth like bundles of rigging on a mast. The Barbarians tried to put out their eyes, to cut their hamstrings; others slid under their bellies, drove a sword in up to the hilt and were crushed to death; the boldest clung to their harnesses...Fourteen of those who were on the far right, maddened by their wounds, turned on the second rank; the Indians seized their mallet and chisel and drove it with all their might into the head joint...The huge beasts toppled over, falling on top of each other. It was like a mountain, and on this heap of armour and corpses a monstrous elephant known as 'Baal's Wrath', caught by the leg between the chains, stayed bellowing until evening with an arrow in his eye.
The phalanx exterminated the remnant of the Barbarians at their leisure. When the swords came they held out their throats and closed their eyes. Others defended themselves to the end; they were killed from a distance, by stoning, like mad dogs. Hamilcar had recommended the taking of prisoners. But the Carthaginians were reluctant to obey him, finding it so enjoyable to stick their swords into the Barbarians' bodies. As they were too hot, they began to work with bare arms, like reapers; and when they paused for breath, their eyes followed a horseman galloping after a soldier running away in the countryside. He managed to catch him by the hair, held him like that for a time, then struck him down with a blow from his axe.
The two thousand Barbarians were tied up against the steles of the tombs in the Mappalia; and merchants, kitchen porters, embroiderers, even women, widows of the dead with their children, anyone who wanted to, came along to kill them with arrows. They took slow aim, to prolong the torment; they alternately raised and lowered their weapons; and the crowd jostled and screamed. The palsied were brought along on litters; many had the foresight to bring food with them and stayed until evening; others spent the night there. Drinking tents had been set up. Several people made a lot of money by hiring out bows.
He came out bent double, with the bewildered look of a wild beast suddenly set free.
The light dazzled him; he stayed still for a while. All had recognised him and held their breath.
This victim's body was something special for them, endowed with almost religious splendour. They leaned forward to see him, especially the women. They were burning with eagerness to look at the man who had caused the deaths of their children and their husbands; and from their inmost heart, despite themselves, surged up an infamous curiosity, a desire to know him completely, an urge mingled with remorse, which transformed itself into an extra degree of execration...
From the place where he stood several roads led off in front of him. In each a triple row of bronze chains, fixed to the navels of the Pataeci Gods, stretched in parallel from one end to another; the crowd was crammed against the houses and, in the middle, walked the Elders' servants, brandishing lashes.
One of them gave him a great push forward; Matho began to walk...[They] cried that he had been allowed too wide a path; and he went, probed, pricked, ripped by all those fingers; when he reached the end of one street, another appeared; several times he hurled himself sideways to bite them, they quickly drew away, the chains held him back, and the crowd burst out laughing.
A child tore off his ear; a girl, hiding the point of a spindle under her sleeve, split open his cheek; they tore out handfuls of hair, strips of flesh; others with sticks on which were stuck sponges soaked in filth dabbed at his face. On the right side of his throat spurted a stream of blood; at once delirium began...The people's rage developed as it was gratified; the chains were too tightly stretched, bent, nearly broke; they did not feel the slaves hitting them to push them back; others clung to ledges of the houses; every opening was full of heads; and the harm they could not do him they shouted...
Shadows passed before his eyes; the town whirled round in his head, his blood streamed out from a wound in his hip, he felt he was dying; his legs folded, and he slowly collapsed on the pavement.
Someone fetched, from the perisyte of the temple of Melkarth, the bar of a tripod red hot from the coals and...pressed it against the wound. The flesh smoked visibly; the people's booing drowned his voice; he stood up... Drops of boiling oil were thrown at him with tubes; shards of glass were sprinkled under his feet; he went on walking. At the corner of the street of Sateb he leaned against the low roof of a shop, back to the wall, and went no further.
The slaves of the Council struck him with their hippopotamus hide whips, so furiously and so long that the fringes of their tunics were soaked with sweat. Matho seemed insensible; suddenly he gathered his forces, and began to run at random, his lips making the sort of noise people make when shivering with intense cold....
Except for his eyes his appearance was no longer human; he was just a long shape, completely red from top to bottom; his broken bonds hung along his thighs, but could not be distinguished from the tendons of his wrists which had been completely stripped of flesh; his mouth remained wide open; two flames came from his eye sockets which seemed to go up to his hair; and the wretch kept walking!
Lamentations of the Flame Princess eat your heart out, right?
Humans are malicious and cruel to animals and each other; we not only inflict pain and misery as a matter of course, but we enjoy it - as Flaubert understood, given the right circumstances, we will fall over ourselves to get the chance to be the one drawing blood. Don't flatter yourself that we're any different to the people of ancient Carthage underneath it all. It's just that the thin red line of law, order and civilisation is a wee bit thicker for us than it was for them. It could break in an instant when the time is right, as the history of the 20th century showed time and time again.
Seen in this light, the worlds of D&D make much more sense imagined as a world not of multiple humanoid races, but one much more like the way the ancients imagined it: there are humans, and there are monsters, and the monsters are not monstrous because they are evil but because of what they symbolise. They are there to be defeated, so that mankind can demonstrate its strength and cleverness. Like the Hydra, the Sirens, or the Erymanthian Boar, they are there to make us fearful, but, ultimately, to conquer.
This means that I increasingly lean towards what you might called a Howardian view on monsters. They should be singular, special, and very difficult to beat - tentpoles, if you like, just as a campaign has its tentpole dungeons. Not there to be evil, but for the PCs to triumph over through wit, skill and strength. Evil, we can leave to ourselves.