Service animals are working animals that have been trained to perform tasks that assist disabled people. Service animals may also be referred to as assistance animals or helper animals depending on the country and the animal's function. Dogs are the most common service animals, having assisted people since at least 1927.

A working animal is an animal, usually domesticated, that is kept by humans and trained to perform tasks instead of being slaughtered to harvest animal products. Some are used for their physical strength or for transportation, while others are service animals trained to execute certain specialized tasks. They may also be used for milking or herding. Some, at the end of their working lives, may also be used for meat or leather.