Mary Marg Helgenberger (born November 16, 1958) is an American film and television actress. Helgenberger is known for her role as Catherine Willows in CSI: Crime Scene Investigation, and her role as KC Koloski in China Beach, for which she won her Emmy. She has received other awards including two People’s Choice Awards and a Screen Actors Guild Award.
Marg (pronounced with a hard "G," unlike the name Marge) Helgenberger was born in Fremont, Nebraska, the daughter of Kay, a nurse, and Hugh Helgenberger, a meat inspector. She is of Irish and German descent and had a Catholic upbringing.