List of Undertale and Deltarune characters

Undertale and Deltarune are fantasy role-playing video games developed by Toby Fox. They take place in different fictional universes, but feature many of the same characters. Undertale is set in a universe where monsters once coexisted with humans, but, after an ancient war, were trapped beneath Mount Ebott and forgotten. The game follows Frisk, a human child who falls into the Underground, a large cave within the mountain, and seeks to escape. In Deltarune, considered a spiritual successor to Undertale, humans and monsters still coexist. The main character, Kris, discovers the Dark World, an alternate realm inhabited by Darkners, the living representations of real-world objects. They embark on a quest to close the Dark Fountains before darkness overtakes the real world.

The following is a list of major characters who appear in one or both games in the series. The characters have been praised by critics and fans for their humor and in-depth characterization shown through different moral choices. Some characters gained notoriety for their ability to break the fourth wall, manipulating gameplay elements normally only accessible to the player, such as saving.