Doctor Hacopian was a physician serving aboard the USS Enterprise-D in 2370.
That year, Doctor Beverly Crusher wanted to consult Hacopian and Selar after it appeared as if a virus had begun to ravage the ship, later determined to be the first case of Barclay's Protomorphosis Syndrome. (TNG: "Genesis")
This doctor was only mentioned in dialogue. The character was named after writer Brannon Braga's chiropractor. (Star Trek: The Next Generation Companion (2nd ed., p. 289))