Note, this article has been updated from the original posted in February 2016.
RPG sage Monte Cook wrote an interesting article called PCs versus NPCs in which he discusses the time we often waste putting together statistics for NPCs. These NPCs, he argues, just show up, talk for a bit, and disappear forever. Here's an excerpt:
NPC (and creature) detail is one of the ways in which designers and GMs are often forced to waste a lot of time. That's because the game has all these great rules for fleshing out PCs and making them cool and interesting. A game that explores how well a PC is at combat, at interaction, at a wide variety of skills and actions, and makes all those things equally interesting is a great game. But then, it comes time to make NPCs.
In the article Monte is referring not just to our typical bartender NPCs but also to monsters and other potential combatants. He uses this article to promote the NPC design methods of the Cypher system (the RPG system that powers Monte Cook's Numenera roleplaying game) which uses a greatly reduced method for building NPCs, both combatants and non-combatants.
That's great for Cypher games, but what about 5e D&D? How can we strip NPC creation down so small that we don't even have to write anything down to run an NPC?
We likely can't design a system as simple the one in the Cypher system for combatant NPCs. Monsters in D&D have quite a bit of crunch to them with their six attributes, hit points, armor classes, attack scores and the like.
Interactive NPCs, however, don't usually need all that stuff. Most of the time they're not likely to draw a sword or get stabbed to the point that they need hit points or an attack bonus. For that quirky bartender we can come up with something simple.
We'll get to the stats in a moment but let's start with the the character's story.
Start With a Good Name
No NPC can exist without a good name. A solid name generator might be the most important tool for the Lazy DM. Whatever your method to find a good name, once we have it, we must write it down. We have no idea which NPC is going to come back again or turn into a major part of the story and the solidity of our world falls apart when our players realize even we don't remember their names.
Use an Archetype from Popular Fiction
Whenever we need all of the physical and behavorial traits of an NPC, we need go no further than our favorite movie, book, or TV show. Think up a character you like, one that pops into your head and loosely fills the role you want and you're all done. If you want to ensure your players don't guess the character, switch the character's gender (thanks to James Introcaso for this tip!). How cool is a female Al Swerengen from Deadwood?
Now on to the mechanics of our instant NPC!
The Divine Art of Making Things Up
At its core, D&D 5e comes down to rolling a die, adding a modifier, and checking it against a difficulty check (DC). In just about any interaction that has a challenge, the DC is all we really need to come up with. And to come up with this, all we really need to do is think about how difficult it is.
Here's some simple math for creating an NPC.
When a PC wants to interact with an NPC in some way that might be challenging for example being diplomatic, lying their asses off, or threatening them; all we need to do is ask ourselves "on a scale of 10 to 20, how difficult is this?". The answer to that question is our DC check.
Any particular NPC may have strengths or weaknesses when dealing with the PC. Maybe they're not very easy to intimidate (DC 16) but might succumb to flattery (DC 11).
This curve isn't perfect. A DC 10 is still potentially a challenge. Many times things will be less challenging than DC 10 and, if they are, we might just skip the roll altogether.
"Roll and Tell Me What You Get"
Another technique, even easier than making up a DC beforehand, is to ask the player to roll a check and then, from the result, tell them what happens. This gets into the idea that there aren't just successes and failures but shades of gray. Someone who rolls really well may get something more than someone who just rolls in the middle. Someone who rolls a 1 might bring some hilarity to the situation.
When you're basing the results of an interaction on an arbitrary roll like this, focus on the total result and not just the die roll. If someone rolls a 2 but happens to be +12 to that particular skill, they might be clumsy about it but will still get the job done. Players want to feel empowered by the points they have in particular skills so even if their roll sucks, that power should be accounted for in the narrative.
The best thing about this "roll and tell me what you get" approach is that there is no math involved at all. It's even easier than Monte Cook's cypher system.
What About Combat Stats?
Coming up with DCs for interactions with NPCs isn't too hard, but what about combat? Again, we can't have a system as easy as the Cypher System for this, though it would be pretty cool if we could. Instead, we can choose one of two systems that still make it very easy.
The first is the easiest and that is to use the NPC statistics in the back of the Monster Manual. We might be tempted to build entirely new stat blocks but most of the time, one of these stat blocks will work. If we need some higher power NPC stat blocks or a bit more variety, we can use the NPCs from either Volo's Guide to Monsters.
If for some reason one of those stat blocks won't do, we can reskin a monster in the Monster Manual or Volo's Guide into something closer to what we want or need. For example, if we want a barbarian warlord who hits like a freight train, we might use the fire giant stat block for the warlord.
Keeping Things Simple
Its easy for us to complicate our lives without really thinking about what we're doing. There's a reason that Numenera has such dead-simple NPC and monster stat blocks—players really don't care about monster statistics. While its nice if a monster does something interesting, much of the time monsters exist to make characters look cool. We might think we need something special but a bag of hit points that the players can smash against to test out their characters is much of what we need.
The same is true for NPCs. A good name, a good character model from popular fiction, a stat block from one of the monster books if we need it, and some idea of how easy or hard parts of the conversation might go is all we really need.
Let's keep our NPCs simple.