The Orff are a sapient species destined to become unwilling hosts of the Yeerks if the Animorphs had lost the war to defend Earth.
Orff are particularly odd sapients, which would almost be considered humanoid in their overall appearance were not for the fact they are tripods and have an extremely long neck. Orff skin appears to be transparent, allowing for others to stare at what appears to be their vital organs. Jake, however, suspects that these visible "organs" are evolutionary decoys, and that their real organs are not visible to their adversaries. Orff see their world through a single large eye, which contains a pupil that never remains in a fixed position.
Orff are capable of limited color changing ability, making them harder to spot. Orff can not go completely invisible however, as their single main eye can give them away, since it glows a bit.
Orff speak extremely fast, much like the Garatron, however Garatron speak telepathically, whilst Orff speak vocally.
Following the Yeerk conquest of Humanity, the Yeerks were able to use this large supply of hosts to conquer other races through sheer numbers. One species in particular were the Orff, who typically serve the Yeerks as law enforcement for the Yeerk Empire. Dozens of Yeerk infested Orff can be found patrolling the under levels of New York City, hunting down and exterminating rebels and the weak. Not all Orff have been enslaved though, and some remain hidden from Yeerk forces, though their numbers are quite small.
Since Jake didn't abandon the Animorphs, this future will not occur, and thus they are never enslaved by the Yeerks.