However, what makes the Vord absolutely terrifying is that they don't just rely on Hollywood Tactics; Vord Queens are brilliant strategists. For instance, the first time the protagonists went up against a hive, the queen got the steadholders to split their forces in half so she could take over quietly, then when the reinforcements arrived Zerg Rushed them from ambush. After inflicting heavy damage, she had her warriors draw back, knowing that the legionaires would take their wounded inside, where she had Takers waiting to turn sleeping soldiers into drones. She specifically targeted the healers and Knights, crippling their combat force. In other words, one five-minute Zerg Rush = half the army down.
Not to mention the Alerans' furycrafting works against them. Normally the Vord don't know how to use the furies, but if someone uses their furies, then the Vord can do the same, making the most powerful weapon the Alerans have useless.
This is the whole reason for the Masquerade in The Dresden Files, by the same author. It is mentioned several times that though supernatural creatures, and even wizards, regard ordinary mortals individually as somewhere between food and pawns, everyone in the supernatural community knows that if the mortals in general ever became aware of the supernatural, they could wipe out all the vampires, fairies, and wizards by sheer weight of numbers.
In Halo: Ghosts of Onyx, this was the purpose of the Spartan-III supersoldiers, since the Spartan-IIs were deemed too valuable to waste. The Spartans would be sent on missions with next to no success rate, in the hopes of stalling the enemy. It's a slight subversion in that they're physically and mentally tougher than the average shock troop, but they're still treated tactically as an expendable resource.
In Halo: The Fall of Reach, Spartan-II John-117 along with the rest of his team observe a formation of roughly 1000 Unggoy (Grunts), and John reminds himself that while Grunts can be cowardly, they tend to attack in such numbers that in several instances where the human defenders kept mowing them down wave after wave, the humans eventually ran out of bullets... at which time another wave of Grunts would step forward.
The forces of evil can also be surprisingly clever tacticians, though, as several major defeats for the good guys show. They just almost always have the numerical advantage and decide to make use of it.
J. R. R. Tolkien had fought in the First World War, and knew the Zerg Rush by his own experience. He modelled the modus operandi of the Orc warfare after the First World War human wave attacks.
In the Warhammer 40,000Grey Knights novel, the Allking of Sophano Secundus had an army with horses and spears that just rushed at the Grey Knights, which Alaric actually thought would have killed them because of sheer numbers. They were able to get away though, suffering one casualty and another with an injury while the army of Sophano Secundus lost countless.
Sheer numbers are the primary thing which made the People's Republic of Haven such a threat to the far more technologically advanced Star Kingdom of Manticore in the Honor Harrington series. In fact, the Battle of Manticore in At All Costs is a classic Zerg Rush strategy, as it's an attempt to claim outright military victory before the Manticorans can get their latest Gamebreaker deployed throughout their fleet.
Though they aren't willing to admit it, the same is even more true of the Solarian League. Complacent in their superiority, they never upgraded their technology during the 20-plus-year Lensman Arms Race between Haven & Manticore and are largely content to throw men and ships at problems. As the Harrington trope page itself says, even their reserves have reserves.
In On Basilisk Station, the drug-crazed Medusan natives try to do this. Given that they have nothing better than breech-loading rifles, they die en masse when the air support covering a bunch of Powered ArmorSpace Marines appears. Those natives have more luck when they ambush a smaller scouting force, which is overrun even as the last surviving member is desperately unloading a Gatling gun with exploding bullets into them.
Treecats use this in taking down the oversized predators of the planet Sphinx namely the Hexapuma and Peak Bear.
In Andy Hoare's White Scars novel Hunt for Voldorius, Voldorius deploys thousands of cultists and conscripted militia against the Space Marines.
In "The Shadow Kingdom", Kull and Brule face a horde of Snakemen.
"Valka! What a killing!" said Brule, shaking the blood from his eyes. "Kull, had these been warriors who knew how to use the steel, we had died here. "These serpent priests know naught of swordcraft and die easier than any men I ever slew. Yet had there been a few more, I think the matter had ended otherwise."
Variation in the New Jedi Order. The Yuuzhan Vong will commonly open battle with a Zerg Rush composed of their slave-soldiers (mostly Chazrach) in order to test the enemy's strength and weed out the weakest. Then they go in themselves to fight the real battle against the remaining, more worthy, enemies (it's an honor thing) and though the Vong are big on brute force, they can be incredibly clever tacticians when they legitimately want to. They end up stopping Zerg Rushes altogether in the last few books as they don't havethe numbers to do it anymore.
This is the primary use of Trollocs in The Wheel of Time. Though larger and stronger than humans, they're too stupid and undisciplined to be very good tacticians (though having human or Myrddraal officers in charge helps some). There are a lot of them, however, so they're generally sent out in massive waves to do as much damage as they can through sheer strength, bloodthirstiness, and weight of numbers. Averted with individual Fists (groups of a hundred Trollocs with one or two Myrddraal) as the smaller size allows the Myrddraal a greater degree of direct control, and they're actually quite clever. On the other hand, this turns the Fist into a Keystone Army that can be killed by killing the commanding Myrddraal, so some eschew the tactic.
Journey to the West - Sun Wukong can generate a near-infinite number of miniature clones of himself. Given that Wukong himself is a Munchkin of the highest order, a Zerg Rush of tiny Wukongs can subdue all but the most powerful opponents. (The owner of a magical fan, for example, dealt with the problem via hurricane-force winds.)
In the Ranger's Apprentice books, this is the strategy the Temujai use; send waves and waves of soldiers at their enemies to crush them, while employing a few skilled archers specially designed to take out opposing leaders. Massive casualties mean nothing to them, because they have reserves.
Eric: "They were discussing strategy when Rincewind arrived. The consensus seemed to be that if really large numbers of men were sent to storm the mountain, then enough might survive the stones to take the citadel. This is essentially the basis of all military thinking."
Second Apocalypse: the scranc were created with Organic Technology to be a biological weapon against humanity and the elf-like Nonmen. They have a literal lust for carnage, will eat almost anything, and reproduce so quickly that they can carpet nations. Although individually they are not particularly dangerous, they attack in waves with no regard for their safety, overwhelming armies with simple attrition. In the north, their staggering numbers defy even the largest armies that humanity can bring to bear.
Any Sven Hassel book. Both Soviets and Germans. With appalling results.
This is explicitly said to be how humans defeated the elves in the Ryria Revelations. Elves are superior to humans in every way: stronger, faster, tougher, more advanced technologically, and more powerful in magic. However, where humans can replenish their numbers in a couple of decades, it takes millennia for elves to restore their losses. As one protagonist puts it, the elves "were drowning in a floodtide of humanity."
The same can be said to Human-Elves conflicts in the back-story in Isekai Light Novel Dungeon Seeker.
In Robert A. Heinlein's Starship Troopers, Rico tells how the Bugs that are fighting against the humans would send soldier arachnids out in massive numbers, and when desperate, even send out harmless workers to cause the humans to waste ammo on them.
Sun Tzu's The Art of War discusses such tactics: such a rush is good for when you know your army vastly outnumbers the other, but heavily discouraged for longer tasks like siege warfare due to the risk of heavy losses.
In Jeramey Kraatz's The Cloak Society, when Cloak appears at the park, acting threatening, the Powers (characters with less than "super" powers) try this on them.
In Dora Wilk Series, the semi-corporeal ghosts manage to take a super-witch Viola down by sheer weight of numbers - they can attack her faster than she can repel them.
In Worm Skitter's tactic against unarmed or unaware enemies is to simply flood them with thousands of insects, all biting and trying to crawl into any available orifices. This is usually enough to bring non-capes and even some capes to their knees, helped by the fact that she can easily send millions of insects against them. Against stronger parahumans she has to adjust her approach.
In The Dinosaur Lords, the horde is, by and large, unarmed and unarmoured, and their one and only tactic is to run at the enemy and tear him apart alive. Considering they outnumber humans by an order of magnitude, don't feel pain or exhaustion, go against an enemy for whom a trebuchet is cutting edge military tech and are led by an Omnicidal Maniac who wants to wipe out everyone, it's a fairly viable tactic.
In The Traitor Son Cycle, humans have better tactics and strategy than the Wild, but the Wild has superior numbers and their individual warriors are more powerful, which is why they often act like this.
In Xanth's third volume, Castle Roogna, Dor finds out that this is why goblins are particularly feared, and not even the King of Dragons will stick around when they turn up (in addition to ethical considerations concerning monsters fighting other monsters). Goblins attack in ridiculously large numbers and can storm castle walls simply by piling up into a living ramp (or recently-living, in the case of those at the bottom of the heap). Individual goblins have such miserable lives that they have no real objection to dying like this and they still have the numbers to swamp the defenders even allowing for the tens of thousands it took to pile up the ramp.