The Five

The Five are a mysterious sapient species.

History
Eons ago, the starfaring Andalites discovered the primitive Venber on their homeworld, a frozen moon known as Venbea. However, another sapient species had discovered them first, known as The Five. A particularly cruel and uncaring race, The Five hunted the Venber of Venbea, and melted the poor Venber (who easily melted down in temperatures above freezing). The melted remains of the Venber had many uses, and The Five used these melted remains as coolants for their supercomputers. The excessive harvesting of the Venber by The Five led to the complete extinction of the Venbers.

When the Andalites learned of the Venber's fate because of The Five, they taught the The Five a "lesson". The Five are likely extinct following their war with the Andalites, which Ax seems to imply during a conversation with rest of the Animorphs.