Zombies are more than the walking dead. They’re a useful paradigm for a range of common scenarios in many genres.

Whenever your hero is facing off against a system or mob rather than an individual, that’s potentially a zombie-class situation. Any given opponent isn’t necessarily that formidable; it’s the sheer numbers that make it so difficult for the hero.

War movies are frequently zombie-class, as are comedies about plucky outsiders. Science-fiction and horror revel in zombie-class situations, from the Borg to the Visitors to those troublesome tribbles.

If you find yourself writing a zombie-class situation, here are some helpful class features to keep in mind:

  • You can’t fight the ocean. In a zombie-class situation, heroes ultimately won’t get far trying to defeat their opponents, who have the advantage of both numbers and replaceability. Rather, your hero must set an achievable goal such as escape, survival, or retrieval of a key asset.

  • Ants vs. Elephants. It’s great to be big, but it’s better to be numerous. Just as heroes will often rally a crowd, opponents can do the same — popular opinion is a hard thing to fight. And look for ways to use your hero’s size (or reputation) against him.

  • Zombie processes. In programming, zombies are bits of code that unintentionally keep running in the background, sucking cycles and threatening a crash. That’s a useful framework for many stories: noble intentions run amok. Just as every villain is a hero, every zombie was somebody’s baby.

  • One of us. In the Romero tradition, zombies eat brains. But this can be generalized to assimilation: your hero has something the opponents need. Can your hero figure out what they’re after — what makes the hero special — before it’s too late?

A zombie-class situation is a key difference between Alien and Aliens.

In the former, Ripley and company mostly battle a single creature. Survival means killing it, so that’s pretty much the only goal.

In the sequel, the aliens are so numerous that there is no hope of defeating them. Rather, Ripley’s goal is simply escape. Once Newt is captured, Ripley must face off against the Queen, but defeating her in no way impacts the hordes of aliens left behind.

That’s how zombie-class situations often end: the hero’s victory leaves the world just as dangerous as before.