Rhynocs are anthromorphic rhinoceroses which inhabit the Spyro universe. They are usually the "slave" for villains such as Ripto.
In Spyro: Year of the Dragon, The Sorceress found a way to turn gems into Rhynocs (as well as other creatures), much like the spell that Gnasty Gnorc used. She made the Rhynocs her "slaves" or her "warriors" and used them to fight off Spyro and to capture all the dragon eggs. The artificial creatures are semi-immortal, they live forever as the same soul, though if they die the Sorceress must bring them back and her only. Chances are that genuine Rhynocs lived in the Forgotten Worlds before the fake ones (similar to Gnorcs).
After The Sorceress' defeat, the Rhynocs discovered that they had no sole purpose until they were adopted by Grendor. Grendor gave them new life by giving back their crystals, he used them also to fight off Spyro in Spyro: Season of Ice. After Grendor's defeat, The Rhynocs once again felt unneeded and useless, until adopted by Ripto. Ripto controlled the Rhynocs when not using his army of Riptocs during the events of the Season of Flame and after stealing the Professor's Laboratory.
Rhynocs have not been seen since.