Annoying Dog is a small, white, cartoon-like dog that appears throughout the game Undertale, often causing mischief and comic relief. Representing the game's creator Toby Fox, the Annoying Dog frequently interferes with puzzles and events, sometimes to the player's detriment. Despite its simple design and lack of dialogue, the character has become iconic among fans for its playful antics and surprises, serving as a humorous and unpredictable presence within the game's world.