Christian was born in Glendale, California, the daughter of Hildegard (née Christian), who worked as the director of Giorgio Beverly Hills, and James Michael Coghlan. Her mother is from Germany and her father has Irish ancestry. She was raised in Connecticut and England. She has two older brothers and currently resides in Los Angeles and London.
Christian's first role on television was a guest appearance on Dallas, followed by a series regular role as Melody Hughes on the short-lived drama Berrenger's. She performed feature film roles such as a stripper possessed by an alien serial killer in The Hidden (1987), a police department psychologist Susan Riley in Maniac Cop 2 and as model Hexina in Hexed (1993).
In 1994–1998, she appeared as Commander Susan Ivanova, one of the series leads, in the first four seasons of Babylon 5. She left unexpectedly when contract negotiations for the fifth and final season – aggravated by the possibility that there would not be one – broke down. J. Michael Straczynski, the series' creator, maintains that she chose to leave on her own. However, Christian stated that she did wish to return for season 5, but was rebuffed and let go when she requested a small reduction in the number of episodes she would appear in. She appeared in the fifth season's series finale, which had been filmed during the fourth season, when it seemed likely that the series would end prematurely.
She posed nude for Playboy magazine in October 1999, appeared in two episodes of Freaks and Geeks in 2000, and appeared in the 2002 She Spies episode, "Spy vs Spy". In 2004, she returned to the live stage (and to Laguna Beach, California, where she had attended high school), starring in the United States Premiere of Michael Weller's play What the Night is For, with Kip Gilman, directed by Richard Stein, at the Laguna Playhouse. She starred in the BBC comedy series, Broken News in 2005. She also plays Janine Foster, mother of Peri Brown, in the Doctor Who audio drama "The Reaping", produced by Big Finish Productions released in the United Kingdom in September 2006.
She voices Anne Manx in the full cast recordings for the Radio Repertory Company of America. The science fiction series is currently shown as in pre-production for "Anne Manx 6". In 2010, Christian appeared in the Showtime series Look: The Series.
She also had a music career, having released a solo album, Once Upon a Time, a single, "Taboo", a collaboration with Claudia Cummings, Claudia Squared, and a collaboration with some of the other cast members of Babylon 5 on the album The Be Five.
Christian conceived her own convention, Claudia Con UK, which took place in the United Kingdom on August 13–14, 2011.
"After years of attending conventions where fans were mistreated, told not to touch, photograph, film, eat or breathe…. I decided to throw what I call the 'anti-convention.' My theory is that if you give people freedom and respect they will in turn give you freedom and respect."
Christian has been publicizing the Sinclair method, a treatment for alcohol dependency, through her book Babylon Confidential. In this book she recalls her own experiences with the condition. She made a documentary titled One Little Pill about the method under the auspices of the C3 Foundation, which she founded."Revenge is a Bitch to Swallow." Short story. Published in Forbidden Love Issue 2: Wicked Women.
My Life With Geeks and Freaks. Autobiography. Published by Yard Dog Press.
"Babylon Confidential: A Memoir of Love, Sex, and Addiction" Autobiography.
Wolf's Empire: Gladiator. Novel, co-written with Morgan Grant Buchanan. 2016.
Claudia Squared with Claudia Cummings (1996)
Trying to Forget by The Be Five (1998)
"Taboo" single (1998, Zard)
Once Upon a Time (2001, Zard)