Munchkin is a card game by Steve Jackson Games, written by Steve Jackson and illustrated by John Kovalic, that has a humorous take on role-playing games, based on the concept of munchkins (immature role-players, playing "to win").

A Munchkin game typically runs about an hour, depending on how many people are playing. At the beginning of the game, "Everyone starts as a Level 1 Human with no class." and attempts to "reach the 10th level".

Each person's turn begins with the player opening a room (kicking down the door) by drawing a Door card face-up and looking for trouble. If there is a monster in the room, the player fights the monster. If the player's level plus bonuses from the player's equipment (such as Sneaky Bastard Sword or Really Impressive Title) is higher than the monster's level plus any bonuses the monster might have (such as Enraged or Buffed), then the player wins the fight, moves up one level (though some monsters grant more levels), and takes the monster's stuff. If there is no trouble in the room, then the player can choose to either draw another Door card face down (looting the room) or fight a monster from his hand (looking for trouble). To prevent opponents from achieving the winning level (9, 10, 11, 20, or 22 depending on pre-game selections and card play), players can give enhancing cards to whatever monsters are fighting the other players so that the monsters will win and cause "Bad Stuff" to happen to the player, or throw curses on each other (or have them happen randomly), such as New Edition Rules (causing all players to lose a level). Players can also use items against each other such as Itching Powder (making the player throw away any clothing or armor). Munchkin rules do not include a stack, which means that every card played resolves instantaneously, with few exceptions (which include the use of the card Wishing Ring to cancel curses). All cards may be played at any time, unless specified otherwise.

Munchkin is not a very serious game; the rules make this clear with phrases like: "Decide who goes first by rolling the dice and arguing about the results and the meaning of this sentence and whether the fact that a word seems to be missing any effect." and "Any disputes in the rules should be settled by loud arguments with the owner of the game having the last word." There are many cards which interact with or are affected by a single other card, despite the rarity of the two cards entering play together (such as the interaction between Fowl Fiend and Chicken on Your Head or Sword of Slaying Everything Except Squid and Squidzilla).