Most of the wildlife observed today can be traced back to creatures of Earth. In the Orokin Age, organic manipulation was used to modify earth lifeforms to a purpose: war, agriculture, pets. Long after their Orokin masters perished, some of these species managed to survive through adaptation, and can be found roaming in natural environments.
—Wildlife Fragment

Beast is one of two categories of Companions that includes Kubrows and Kavats, with the other being Robotic that includes Sentinels and MOA. A distinctive feature from robotic category is the need for daily maintenance which, if skipped - will cause a deterioration in the beast's performance. Additionally, there are mods that can only be equipped by this category of companions. If killed in a mission, beasts (and robotic MOAs) can be revived infinitely, unless their bleedout timer runs out, in which case they will automatically revive after the owner is killed and spends a revive, or always in the next mission.

Main article: Kubrow

Kubrows are terrain-restricted melee canine companions. Kubrows behave similarly to NPC allies (i.e. specters) as they will stay within close proximity of the player while fighting alongside them and will enter bleedout states when they are downed, from which they can be revived. Incubated Kubrows have variable permanent traits such as species, height, and eye color, as well as customizable features like fur color and fur pattern. There are currently 6 species of ownable Kubrows, each with different stats and abilities.

Main article: Kavat

Kavats are terrain-restricted melee feline companions similar to Kubrows. They also have different breeds, color palettes, and patterns. There are currently three types of Kavats.

Main article: Predasite

Predasites are terrain-restricted Infested companions. There are currently 3 subspecies of Predasites.

Main article: Vulpaphyla

Vulpaphyla are terrain-restricted Infested fox-like companions. There are 3 subspecies of Vulpaphyla.