The dog who serves as the player's assistant in Animal Crossing: New Horizons is Isabelle.
Isabelle is a golden Shih Tzu who helps run the island’s Resident Services alongside Tom Nook. She provides island evaluations, announces daily updates, discusses ordinances, and supports the player as the settlement develops. Her role makes her one of the game’s most recognizable guides, although Tom Nook remains the main business and infrastructure manager.
Isabelle debuted in Animal Crossing: New Leaf, where she worked as the secretary to the player character after the player became mayor. The developers created her specifically because a player-controlled mayor needed an assistant. Her Japanese name is Shizue, and she has a twin brother named Digby, who is associated with the Happy Home Showcase.
Players sometimes confuse Isabelle with K.K. Slider because both are dogs and major Animal Crossing figures. Their jobs are completely different: Isabelle handles administration and player support, while K.K. Slider is the traveling musician who performs concerts and provides songs. Isabelle also appears outside the series, including as a playable fighter in Super Smash Bros. Ultimate.