There are a plethora of synonyms for the term "animal sidekick." Some of the most common include companion animal, animal friend, furry friend, four-legged pal, and partner in crime. Other options include beastly buddy, critter comrade, pet partner, and trusty steed. For creatures that are more exotic or fantastical, terms like mystical familiar, magical companion, or spirit guide may be more appropriate. Ultimately, the term chosen depends on the unique relationship between the animal and their human counterpart. Whether a loyal service animal or adventurous adventure partner, there is sure to be a synonym that accurately captures the importance of these beloved animal companions.