(written from a Production point of view)
Maryann Plunkett (born 1953) is the actress who portrayed Lieutenant Commander Susanna Leijten in the Star Trek: The Next Generation fourth season episode "Identity Crisis" in 1991. She filmed this episode between Wednesday 16 January 1991 and Friday 25 January 1991 on Paramount Stage 8, 9, and 16. A distressed Starfleet uniform worn by her in this episode was sold off on the It's A Wrap! sale and auction on eBay.  In 1994 she voiced the part of Lieutenant Terra Spiro in the Captain Sulu Adventures audiobook story Cacophony.
Personal and stage career Edit
Plunkett was born in Lowell, Massachusetts, graduated from the University of New Hampshire, and is married to actor Jay O. Sanders since 1991. The couple has one son, Jamie Sanders, born in 1994.
Plunkett worked as replacement in the Broadway plays "Agnes of God" (1982-1983) and "Sunday in the Park with George" (1984-1985) before she landed the lead role of Sally Smith in "Me and My Girl". She played this part between 1986 and 1989 and received a Drama Desk Award nomination for Outstanding Actress in a Musical in 1987 and won a Tony Award for Best Actress in a Musical in the same year.
Further Broadway plays include "The Crucible" (1991-1992, with Fritz Weaver), "A Little Hotel on the Side" (1992), "The Master Builder" (1992), "The Seagull" (1992-1993), the title role in "Saint Joan" (1993), and more recently "A Man for All Seasons" (2008) at the American Airlines Theater in New York City. 
Soon after her Broadway debut, Plunkett started to work for television. She made guest appearances in episodes of Miami Vice (1984), American Playhouse (1985, with Shay Duffin), A Man Called Hawk (1989, starring Avery Brooks and directed by Winrich Kolbe), Matlock (1990, with Raymond Cruz, David Froman, John Hancock, and Mark Moses), and L.A. Law (1990, with Corbin Bernsen, Larry Drake, Nicolas Surovy, Jennifer Hetrick, Craig Wasson, Diana Muldaur, Warren Munson, and Megan Parlen).
She also had supporting roles in the television movies The Littlest Victims (1989), Deception: A Mother's Secret (1991, with Steven Weber and Charles Emmett), and Breaking the Silence (1992, with Fran Bennett, Jill Jacobson, Kevin Conway, and Frank Novak).
Beside three different roles in three episodes of the hit television series Law & Order in 1996 (with Carolyn McCormick), 1998, and 2002 (with Lynnda Ferguson), Plunkett worked on episodes of Murder, She Wrote (1995, with Robert Foxworth, Scott Marlowe, Nicolas Surovy, and Leslie Bevis), Damages (2010), The Good Wife (2010), and Rubicon (2010, with Concetta Tomei).
Plunkett made her feature film debut in the 1997 comedy Fools Rush In with Josh Cruze, Christopher Michael, Andrew Hill Newman, and Leslie Silva. The following years she appeared in the drama Claire Dolan (1998, with Colm Meaney and John Doman), the music drama Center Stage (2000, with Jeff Hayenga, Zoe Saldana, Donna Murphy, and Scottie Thompson), the drama The Squid and the Whale (2005), the drama Brooklyn Lobster (2005), the thriller The Night Listener (2006, with Becky Ann Baker), and the drama Peter and Vandy (2009).
More recently she worked on the drama The Company Men (2010, with John Doman), the romance Blue Valentine (2010, with John Doman and Mike Vogel), and the comedy Fairhaven (2012).