A character class is a fundamental part of the identity and nature of characters in the Dungeons & Dragons role-playing game. A character's capabilities, strengths, and weaknesses are largely defined by their class; choosing a class is one of the first steps a player takes to create a Dungeons & Dragons player character. A character's class affects a character's available skills and abilities. A well-rounded party of characters requires a variety of abilities offered by the classes found within the game.

Dungeons & Dragons was the first game to introduce the usage of character classes to role-playing. Many other traditional role-playing games and massively multiplayer online role-playing games have since adopted the concept as well. Dungeons & Dragons classes have generally been defined in the Player's Handbook, one of the three core rulebooks; a variety of alternate classes have also been defined in supplemental sourcebooks.