I took an atypical path to tabletop gaming, and I’ll probably talk about that in more detail one day. The first D&D book I ever picked up was the 3.0E Monster Manual, and when I opened it the first monster I saw was this one. I don’t know if that’s why I like them so much, but it couldn’t have hurt.
Minotaurs are half-bull, half-human creatures you’ve probably already heard of, if not from Greek mythology then from playing Tauren in World of Warcraft. Given that original capital-M Minotaur lived in a maze, they typically have some resistance to getting lost or some bonus to determining direction. In every edition I can think of they’re also really good at charging enemies, because that’s what bulls do. Beyond that they’re vanilla, low-level beatsticks.
Most editions go out of their way to not talk about minotaur society. After all, monsters only exist as things to punch on the way to a reward. It doesn’t matter whether they have legends or hobbies or religion, only that they like mazes and they generally charge in the first round of combat. But their simplicity is a lot of what made them viable monstrous PCs. As long as you can wrap your head around Effective Character Level as a concept, you already know everything you need to be a minotaur. There are no weird powers, no strange interactions with spell casting classes, no abilities that require three other books to fully understand. Just a few physical buffs and some Hit Dice. It’s like the Lolth-touched template with legs.
The first monstrous PC I ever saw was a minotaur, but that’s not my story to tell. I can tell you about Kulgrim of the Held Fist, the first NPC in the Unnamed Monster Campaign, where the players were all monstrous PCs. The party was tasked with killing a minotaur who had been terrorizing the locals. When they found that minotaur, he was meditating under a waterfall. After a very short period of confusion, he agreed to help the players kill the real culprits, and that set the stage for an entire campaign about being the good guys when you look like the bad guys.
I think the players liked him for the limited amount of time he appeared on screen, though he didn’t leave a strong impression, and that was the point. A minotaur monk wasn’t supposed to be a unique, weird thing. It was supposed to be normal, and to redefine “normal” in the context of the campaign. The players mostly remember him for being a skeleton (he wasn’t, but that was the only minotaur miniature I had at the time), and for this exchange:
DM: You see a minotaur meditating under a waterfall. He opens his eyes as you arrive and greets you.
Player: Spot check for a weapon in the minotaur’s pants!
DM: Um.
Other players: Um
Other people passing by: Um.
Player: No wait stop. I want to see if he’s hiding something. Because the pants are wet, right? So they cling.
DM: Um.
Player: Never mind.
Weirdly, the edition where minotaurs get the most character is the official edition of ignoring fluff text, 4E:
However, many minotaurs are civilized and cultured. These minotaurs are smaller than their savage kin, and they gather in settlements of all sizes.
This is a nod to the appendix at the end of the book, which had minotaurs as a playable race. They wouldn’t really be part of the system until Player’s Handbook 3, but even the Core books said “look, not every monster is…well, monstrous.” I just wish it wasn’t tucked away in the lore section of a monster so common few think to read its lore at all.
Lolth-Touched creatures are people and monsters given power by Lolth, goddess of drow and spiders and best friend to every author who couldn’t think of a more interesting villain in Faerûn. Her blessing makes them better in melee (curious for a deity whose favored race hates melee combat, but whatever), gives them a few cute but mostly trivial buffs, and makes them evil. Because it’s a template, there’s not a lot of additional story here. Lolth like thing, thing get stronger.
Scientivores were creatures that ate knowledge, in the same way that herbivores eat herbs and carnivores eat 
In the Eight Arms and the Shadow Invasion, the players started off the campaign fighting shadow creatures, began fighting light creatures in Act 2, and ended up in a three-way free-for-all against both factions. The light-based enemies were shored up by jyoti, who brought a martial aspect to the fight without blinding everybody, enemy or ally, nearby. They were a decent CR for the party, such that the players could fight three or four of them at once in an ostensibly balanced encounter, and they were close enough to harpies and other winged creatures that I could use the minis I had on hand for them. They fit perfectly.
Enter Eligio, ice elemental warrior with a Wisdom of 4, who believed anything and everything you said to him. When he fought alongside the party and defeated the villain on that floor of the tower, he gained a level and sufficient will to ascend it himself. He showed up a few times from then on, usually allied with the party, and though he joined their enemies late in the campaign he died off-camera before they could fight him. Eligio became such an endearing character that he also showed up a few times in Delve Night, our 
My intention in the first Zelda campaign was to have a villain who was not Ganon. I thought a group of mid-level players wouldn’t be powerful enough to fight the actual Ganon, and I thought a different villain would lead to a more interesting story. Over the course of the campaign I realized how much the players really, really wanted to fight Ganon anyway, but I wavered on it because didn’t fit what I was doing. Come the final session, the final boss turned out to be really underwhelming and she largely went down without too much of a fight. The campaign wasn’t ending on a good note, and we still had some time left in our gaming block. In a pinch, I flipped through the books real quick to find a creature who kind of fit Ganon’s build, wasn’t too complicated, and sat at an appropriate final boss CR. The hezrou fit the bill, so I reskinned his stench as an aura of evil, the same thing that prevented the player from targeting him in Ocarina of Time.
I’d like to say this taught my players a valuable lesson about asking the questions to which they want answers instead of asking something similar and assuming other people understand their meaning, but that’s not even a little true. It also did not teach the players not to go to the grodair for help. Because they spent the campaign apart from any sort of information network and without a means to call for help, I gave them an NPC sage who could answer questions about monsters for them. Because the NPC was helpful, they immediately assumed it was an enemy plant, even though they didn’t assume that about anybody else who was assisting them. Instead they opted to deal with the insufferable fish rather than the NPC who wanted to help because the fish was exactly frustrating enough to be trustworthy.
But I ran a Zelda campaign, so I had to include their bat equivalent, keese. And since keese were one-hitpoint minions, I could throw them in pretty much at any level as a way to annoy my players whenever they showed up late for game too often. We also had an escalation of that mechanic, which we called super-minions: creatures who became bloodied after one hit and died after a second. It meant they weren’t completely invalidated by any persistent or automatic damage, but never so serious that they were a real threat except in the context of the monsters they accompanied. Fire bats, or here fire keese, were super-minions. If they took damage or hit an opponent, they lost their flame, and almost any damage dealt to a flameless keese killed it. The exception was fire damage, which healed them back up to full hit points (which, to be fair, was 2).
He dubbed the stranger “Señor Risco”, and to be honest I have no idea why. I vaguely recalled that “risco” was Portuguese for “rock”, and earth elementals spoke Portuguese because of some one-off gag from a previous session. A quick check now proves that’s nowhere near the correct translation, but whatever, the name stuck. We got Señor Risco a luchador’s mask, then realized he could not earth glide with the mask on, so he followed the party mostly hidden with only his head sticking out of the ground. From there the jokes kept piling on and he became something like a member of the party, perhaps even more than the cohort who was doing all of our healing. When the campaign ended he was thirty feet tell and he had taken the feats he needed to perform tag team maneuvers, which were mostly picking up the slowest members of the party and throwing them to (at) their enemies.
The Portalator was a shopkeeper who managed portals to various other planes and places within them. I think he was in the Abyss, and he came up when the party wanted to work their way to a demon prince who had been harassing them and give him what for. He was forward, personable, and maybe ever so slightly incredibly camp. From the very first word he uttered, he was clearly not a typical slaad and became unique enough for the players to recognize and dread him from them on. He turned against the party for reasons I honestly don’t fully remember, and at the end of the campaign’s second arc he managed to kill the cleric with a save-or-die right after she used one against his team. They got their revenge against him in the third arc…I think. I’m not sure they ever found the body.