Mary Marg Helgenberger was born on November 16th 1958 to Hugh and Kay Helgenberger in Fremont Nebraska. Marg grew up in North Bend on the Platte River with her sister Ann and brother Curt. 

She attended Kearney State College and transferred to Northwestern Alumnus School of Speech, Evanston, IL. Marg majored in Speech and Drama. She caught the acting bug the when she landed role of Blanche Dubois in a university production of A Streetcar Named Desire. 

A scout for Ryan's Hope discovered Marg when she performed in an NU campus production of Shakespeare'sTaming of the Shrew as Kate, summer of 1981. The scout offered Marg a possible role on Ryan's Hope and Marg wanted to finish college first. So she promised to check back with Marg and she did. Hence, her first professional acting role as the charactor Siobhan Ryan. 

In 1984 she met Alan Rosenberg a guest actor portraying a pimp on RH. She thought he was handsome and they started dating in 1986. They married in 1989 and have one son Hughie named after Marg's father, Hugh Helgenberger. 

Marg's work as been honored by receiving The Q Award (Viewers for Quality Television) three years consectively, 89, 90 and 91 for Best Supporting Actress in a Quality Drama Series, China Beach.) In 1990 she won an Emmy for Outstanding Supporting Actress in a Drama Series, China Beach. She was also nominated for an Emmy in 91 and 92 respectively for China Beach. She was Emmy nominated for her work as Catherine Willows on Crime Scene Investigation Emmy Outstanding Lead Actress in a Drama Series (2000).