Kalen Tarcoh was a tall, middle-aged Deltan male living on starbase Vanguard in the 2260s. Doctor Tarcoh was a civilian theoretical physicist assigned to the Vault, Vanguard's secret laboratory. On August 1, 2267, the Vault was flooded with toxic gas from a fire and Dr. Tarcoh had to be helped to evacuate by Dr. Carol Marcus and Lieutenant Ming Xiong. (VAN novel: Precipice)