Viktor Kharkov was a researcher and archivist part of the team sent by the UAC to Mars after the events of Doom 3 and the UAC's renewal of their Mars program.
His emails are discovered in several PDAs picked by the player in Doom 3: Resurrection of Evil, however he is never encountered throughout the campaign except for his body being found in the room where the artifact called the "Primitive" is stored. His PDA is lying close to him. It appears that he has made research concerning The Hunters, the demons that Betruger sent after the Marine Engineer in order to recover the Heart of Hell artifact from him. It is also revealed that he was trying to contact his wife, Katherine, who is on Earth, but his emails did not reach her.