Kobal, in that dinosaur game, how many human hunters are there?
So far, it looks like Ogre and Dungeon Keeper qualify, Overlord might, and MMO boss raids sort of qualify with an asterisk (since each player only controls one character).
That reminds me of the game Evil Genius, which had a similar setup. You control a lair full of minions and henchmen. Although the world governments send various weak units against you, every so often you have to deal with a super agent (think James Bond) that requires most of your forces to defeat. Had a great soundtrack as well.
Evolve.
Dungeon Keeper is more many, vs less. Some levels have rolling waves of weak heros coming in, others might have had a few strong heros, but I can’t remember any level where you had to stop only a single powerful hero.
I loved that game, I’d play the Fu Man Chu character. It was like The Sims for megalomaniacs. You relied as much on traps as you did minions but the “many on one” thing applies I guess.
I think my favorite part was catching a super agent then gloating as you tortured them.
Yeah Evil Genius was good fun, but you’d spend as much or more time fighting your goons’ AI and pathfinding as plotting against the “heroes”. Did you know that contrary to intuitive knowledge the best strategy re: fire is to have only one fire extinguisher on your entire base ? Here’s why : when a fire breaks out, the first minion informed will go find the closest extinguisher as the crow flies. And nobody else will take out the fire, because someone’s already on it. Also only the lowest level social goons will ever use them - nobody else.
So if a fire breaks out in view of a camera and you have a robust speaker system, you might see a random valet in a hotel halfway across the island run towards the extinguisher closest to them (which may or may not be in the same part of your lair as the fire at all) then try and route to the fire. Meanwhile, goons sitting next to the fire and with an extinguisher three steps down the hall will not move, because someone’s already coming. Also meanwhile half your base is a roaring inferno. Oh, and when the valets get to the burning thing, your troubles are not over : they’ll extinguish one or two burning objects, tops. Then they go put the extinguisher back on its wall (so, one more longass trip) because they’re not the active minion designated for the other, new fires. You see there’s already another valet en route to deal with them from halfway across the island…
If you were not a mad evil genius screaming at being surrounded by idiots and pulling your hair before, you are now 
While it’s normally many-on-many, Stellaris occasional has battles of an entire fleet of starships against a single powerful opponent. The “Guardians” from the Leviathans DLC like the Ether Dragon, Stellarite Devourer, and Dimensional Horror.
Didn’t Baldur put you in charge of a group where you told all your follower characters what to do when you went into combat? Been quite a while since I played it.
You mean, Baldur’s Gate? That was six characters, not really enough to qualify as “many” or “an army”. I mentioned RPGs as typically being “few vs.” in the OP.
The closest thing I can think of offhand, aside from the mastermind/lair type games already mentioned, is probably Attack on Titan: Wings of Freedom. The action is focused on one viewpoint character at any one time, but you can assemble a small squad and direct their actions in attacking the giant enemies. Many missions also include other soldiers on your side doing various things around the map–setting traps, fighting, providing resupply, needing to be rescued (especially this last one). It’s a very fast-paced action game, and the squad controls are pretty simple, of necessity.
For anything larger than a small squad, I think you’d have to be looking at something turn-based or RTS, just because of the difficulty in controlling large numbers of characters in a more action-driven game.