Random Encounter Generator 5e
Pick where the party is and how hard it should be. Get SRD monsters that fit the terrain and the XP budget, plus a reason they're here and something to complicate it.
Should something happen? Roll a d20; 18+ means an encounter.
Your encounter
Choose a terrain and roll.
Making random encounters matter
A random encounter should reveal something about the world: who controls this road, what's hunting in these woods, how close the villain's reach extends. Before you run the fight, ask what the creatures want. A wolf pack wants food, not a war; bandits want coin with the least risk.
Terrains and what lives there
Forests hide wolves, spiders, owlbears and green hags. Mountains bring harpies, griffons, ogres and, at higher levels, wyverns and red dragons. The Underdark crawls with duergar, grick, oozes and driders. Swamps have lizardfolk, crocodiles, will-o'-wisps and hydras.
Questions
How does the random encounter generator pick monsters?
It filters the SRD monsters by the terrain you choose, then builds a group whose total XP lands inside the party's budget for the difficulty you asked for, using the 2024 encounter budgets. Each result also rolls a reason the creatures are there and a twist.
How often should I roll random encounters?
A common approach from older editions: roll a d20 every few hours of travel or once per watch at night, with an encounter on an 18 or higher. Many DMs make half of those non-combat meetings.
Can random encounters be non-combat?
They should be, often. Every result includes what the creatures want. Hungry wolves might be driven off with food; bandits might prefer a toll to a fight.
Where do the monsters come from?
From the free System Reference Document, so every stat block is available at no cost in the SRD.