Janssen hails from either Amsterdam. While she moved to the U.S. in 1984 she began her professional career as a model and worked for Yves Saint Laurent. Fallowing researching stagecraft at Columbia University she moved to Los Angeles where she appeared within guest roles in TV series (like Star Trek: The Next Generation and Melrose Place). Before long fallowing, she appeared in the 1st Pierce Brosnan James Bond film GoldenEye making an impression on the cinema world when Xenia Onatopp. She is better known for her role when Jean Grey in X-Men and X2, and too per moving picture Lord of Illusions, Rounders, and Deep Rising.

Janssen besides got the large role in the 2nd year of the popular TV indicate Nip/Tuck, as seductive & manipulative life coach Ava Moore. This character was unforgettably revealed to become the male-to-female transsexual within late episodes.

Selected filmography
Fathers & Sons (1992) - Kyle Christian Relentless IV: Ashes to Ashes (1994) - Dr. Sara Lee Jaffee Lord of Illusions (1995) - Dorothea Swann GoldenEye (1995) - Xenia Onatopp Dead Girl (1996) - Treasure City of Industry (1997) - Rachel Montana Monument Ave. (1998) - Katy (known internationally as Snitch) Gingerbread Man, The (1998) - Leeanne Deep Rising (1998) - Trillian St. James RPM (1998) - Claudia Haggs Celebrity (1998) - Bonnie Rounders (1998) - Petra Adventures of Sebastian Cole, The (1998) - Fiona Faculty, The (1998) - Miss Elizabeth Burke House on Haunted Hill (1999) - Evelyn Stockard-Price Love & Sex (2000) - Kate Welles Circus (2000) - Lily X-Men (2000) - Dr. Jean Grey Made (2001) - Jessica ''Don't Say a Word (2001) - Aggie Conrad I Spy (2002) - Special Professional Rachel Wright X2 (2003) - Jean Grey Eulogy (2004) - Judy Hide and Seek (2005) - Katherine Carson The Four Saints (2006) The Treatment (2006) X-Men 3'' (2006) - Jean Grey/Phoenix