Callas was a 23rd century Human man, a member of Starfleet. By the 2260s decade, Callas held the rank of captain and was commanding officer of the Constitution-class starship USS Potemkin. In the year 2267, he commanded Potemkin and relieved the USS Enterprise at Parathu'ul. (TOS novel: The Disinherited)


USS Potemkin personnel
USS Potemkin (NCC-1657) J. ArmstrongArvielaS. AscherD. BaileyT. BarrowsCallasM. ClearyD.M. FlinnM. GarsonJ. GaynorGladstoneJonesyL. KelsoKonstantinR. LonerganD. ParisM. RahdaH. TakeshewadaTutakaiN. UhuraYellowhorse UFP seal Starfleet Command logo
USS Potemkin (NCC-18253) W. T. Riker