Sparx is the dragonfly companion of Spyro the Dragon. He is with Spyro wherever he goes, and that often involves going into some treacherous territory. Sparx is depicted in the Spyro the Dragon series as Spyro's best friend and "health meter". His color varies, being a bright, vibrant yellow when Spyro is at full health, a less vibrant blue when Spyro is at 3/4 health, a dull green for 2/4 health, and missing altogether when Spyro is down to his last piece of health. Sparx is easily revived/healed by the consumption of butterflies, his favorite treat, which can be found by killing the local wildlife.
Sparx is also useful as a "gem magnet". When Spyro passes gems, Sparx will grab the ones close enough to the young dragon, making collection of the gems much easier to do.
Sparx also has a small role in Year of the Dragon as the sort of guide into speedway levels, the levels in which Spyro flies about eliminating all the different enemies to obtain more orbs. Also in Year of the Dragon, he gains an even bigger role with his own levels (small areas Spyro can't get into but Sparx can thanks to Zoe) each with their own set of gems, dragon eggs, and an ending boss in order to gain new abilities, such has increased health and being able to detect gems.