CASTs, also known as androids, are a race in the Phantasy Star universe.
Phantasy Star Online
Androids, as they were known in PSO, are created and therefore cannot use techniques in Phantasy Star Online. They can, however, recover HP by standing still and use Traps to hinder monsters. In Phantasy Star Online Episode III C.A.R.D. Revolution, android has been considered an offensive term to the CASTs and has been replaced by humanoid.
Phantasy Star Universe
"Casts were originally created to serve humans, but the emergence of self-aware casts with free will led to a long and heated struggle over human and cast rights. Years of strife led to the current system, in which casts dominate the administration of human society on Parum.
The rational, logical approach favored by casts is a large advantage in managing a planetary government, but they have a tendency to be relatively strict and inflexible.
Casts can summon and use SUV weapons."
Phantasy Star Portable 2
CASTs are one of the four races of the Phantasy Star universe. Evolved from synths, and the main structure that formed a copy-cast.
Phantasy Star Online 2
In Phantasy Star Online 2, CASTs are one of the four races available for player creation. As with the Newman and Deuman races, they were created from Humans, designed to control aptitude with Photons. As research in the properties of Photons progressed, CASTs became adept in Photons in ways nearly identical to that of Humans, thereby making their differences merely aesthetic.
CASTs were once used as alternative bodies for those with enormous Photon aptitude. Due to the sheer randomness of Photon aptitude in 1st Generation ARKS, those whose aptitude exceeded the limits of their human bodies, such as Regius and Maria, were transformed into CASTs. Humans may undergo a procedure to become a CAST, sacrificing a large majority of their original bodies in place of a CAST body. Organic tissue from a transfer still remains, enabling CASTs to reproduce.