Kelbrid

The Kelbrid are a fierce race of aliens who live in a section of space known to the Andalites as Kelbrid Space.

History
At one point in time the Andalites came in conflict with the Kelbrid that ended with a treaty formalizing a border between their two races.

After the Yeerks lost the war on Earth, the remaining Yeerks fled into Kelbrid Space, trusting that the Andalites and their human allies would not follow.

However, the Animorphs pursued, disguised themselves as criminals to preserve the treaty. Strangely during their exploration of Kelbrid Space, the Animorphs saw no signs of Kelbrid activity, as the sector was oddly empty of any signs of intelligent life.

Culture
Very little information is given on the Kelbrid, with even the Andalites reporting to never have seen a Kelbrid before due to the enforced isolation.

Source

 * The Beginning