Olga is a character who makes a one-time appearance in the Season 2 episode titled "Fallen Angel".
Olga is some kind of medical technician who assists Dr. Karl Kruger in his lab. She administers the truth serum to the captive Archangel on Kruger's orders. Later, she and two nurses are with Archangel when Hawke and Maria von Furster break into the lab to the rescue.
Olga does not appear to have any lines in the episode. Her name is not mentioned explicitly in the episode dialogue but it is given in the closing credits.