Better Angels starts up with the Walker invasion that took place during Season 2 of The Walking Dead. The tactics of Rick and Shane are notably similar when defending Carl from the Walkers.
Downfall has this tactic both played straight and inverted. The Exequia Troops of Unohana's army are mindless drones that employ this tactic occasionally as skirmishers. They are repeatedly shown to pose occasional difficulty to even Lieutenant-strength opponents due to their sheer tenacity. They make no soundnot even when they're hurt or killedand will keep coming until they're dealt a fatal injury.
In Enemy of My Enemy, the Brutes try a version of this, charging in a solid wave of fur and fury against a wall of Jackal-shield-wielding Elites, in a scene reminiscent of soccer hooligans rushing a fence. In this case, the fence pushes back and holds firm, while the Elites' human allies fire down on the Brutes. It's stated that the Brutes were so tightly packed, dozens were dead on their feet because there was no room to fall to the ground once they were killed.
Which is, unfortunately, Truth in writing, as many examples of people dying in tightly packed areas do feature corpses that are only revealed to be such when the place starts thinning out, causing them to fall down due to no longer being supported by the people around them.
Discussed between Atvar and and Kirel before the invasion of Earth in Worldwar: War of Equals. The Conquest Fleet consist of 35,000,000 infantrymales and note that no Human military can match them in those numbers. This tactic actually works in some of the small countries of Earth, helps dominate the skies, and gives superpower nations such as America and China a run for their money.
In Being Dead Ain't Easy, when in the Soul Room, hundreds to millions of Funny Bunnies swarm Joey and Kaiba.
In Queen of the Swarm, Taylor has the potential to do this but hasn't due to lack of Zerg. Though she is looking to fix this for when Leviathan attacks.
America's Stepbrother, America's Enemy V2.0: The Oceanian military's only tactic, as in the original George Orwell novel, the Forever War between the three superstates was effectively a mere song-and-dance routine that was just meant to rally the population in nationalistic fervour and none of the belligerents actually intended to win. Faced with an actual military superpower that does intend to win the wars it fights, the Oceanian military leadership really has no idea what to do besides "throw forces at them and hope for the best".
In Neither a Bird nor a Plane, it's Deku!, Izuku, All Might, and Firestorm are swarmed by hundreds of robots inside Mt. Fuji. Firestorm manages to take out the majority of them while Izuku runs to find his spaceship, but they're besieged by even more robots when they confront the Villain responsible.
In the Gunslinger Girl fanfic "Death in Scampia", an Agency team find themselves surrounded by gang soldiers of the Camorra, backed up a hostile crowd of locals hurling rocks and abuse.
Here were the gunslingers of the Camorra clans, cheap and expendable and inexhaustible in supply. Any other time they would have been an object of derision to the cutting-edge killers of the Agency. Now the girls could sense their handlers' fear and the knowledge made them taut like a mainspring, ready to erupt into a murderous frenzy that would not stop until everyone was brought down in a hail of bullets.
In Chapter 34/35, most of the latter part of Ash's battle in the Saffron Gym amounts to this. While Ash and his Pokémon manage to hold their own for a while against the hordes of Sabrina's Psychic-types, eventually they start to wear out. Fortunately, Dexter manages to bring every Pokémon Ash has caught with the help of his Exeggutor herd (who can use Teleport) to level the playing field.
Red in his Five Island Interlude is forced to deal with this with the Rocket Grunts in the warehouse, though it's a more gradual example, as the plan is to lure him deep into the hideout to take all of his Pokémon. He's saved by a combination of managing to improvise on the fly, and the timely arrival of Yellowwho broke out of captivity with Ratty's help.
Dekiru: The Fusion Hero!: During the USJ incident, Class 1-A, even separated, is doing fine against the League of Villains as most of them are two-bit thugs that even they can handle. However, there's so many of said thugs that it's actively preventing them from reuniting at the entrance. Those at the entrance can't leave to help either, as they're being besieged by villains as well on top of having to protect their two severely injured teachers.