The following individuals made up the science party assigned to the research station on Psi 2000. The USS Enterprise was assigned to pick up the six observers in early 2266, when they were all discovered to be dead.
Engineer
This engineer was found dead in the console room of the observation station as a result of his polywater intoxication. Following his death, it was reported by Joe Tormolen that he died at his post with all life systems off, "frozen there like he didn't care." (TOS: "The Naked Time")
The engineer was played by an unknown actor, or possibly no one at all. His suit was described in the final draft of the "The Naked Time" script, dated 28 June 1966, simply as "heavy gear".
Man in shower
This crewman was found frozen to death in a shower while fully clothed. (TOS: "The Naked Time")
Details of this crewman's demise was later vaguely remembered by Commander William T. Riker in 2364, when a crewwoman aboard the SS Tsiolkovsky experienced a similar death. He requested the assistance of Lieutenant Commander Data in locating the information in the USS Enterprise-D's library-computer information, based solely the recollection "a vague memory of reading somewhere about someone taking a shower in his or her clothing," believing there to be a connection between the two incidents. (TNG: "The Naked Now")
This crewman was only mentioned in dialogue.
Phaser pistol shooter
This crewman was found dead with a phaser pistol in his hand, having "used the computer room as if it were an amusement gallery," according to Spock. (TOS: "The Naked Time")
This crewman was only mentioned in dialogue.
Woman in corridor
This crew woman was strangled to death in the corridor near the console room. (TOS: "The Naked Time")
This woman was portrayed by a mannequin. Her apparel was described in the final draft of the "The Naked Time" script as "in a costume identical to those worn aboard the Enterprise by women crew members" [...] "definitely not dressed to confront the cold."