(written from a Production point of view)
Gwynyth Walsh (born 1955) is the actress who portrayed the Klingon Duras sister B'Etor in the Star Trek: The Next Generation episodes "Redemption", "Redemption II", and "Firstborn". She also portrayed B'Etor in the Star Trek: Deep Space Nine first season episode "Past Prologue" and in the seventh Star Trek film Star Trek Generations. In addition, Walsh played Chief Examiner Nimira in the Star Trek: Voyager fourth season episode "Random Thoughts". In 1998 Walsh provided her voice for B'Etor in the video game Star Trek: The Next Generation - Klingon Honor Guard.
Walsh filmed her first Star Trek episode "Redemption" on Monday 15 April 1991 and Thursday 18 April 1991 on Paramount Stage 16. For the episode "Redemption II", Walsh filmed her scenes on Monday 15 July 1991 and Wednesday 17 July 1991 on Paramount Stage 9 and 16. For "Random Thoughts", she filmed her scenes between Thursday 28 August 1997 and Thursday 4 September 1997 on Paramount Stage 8, 9, and 16.
She was interviewed by Ian Spelling for the Star Trek Generations - Official Movie Souvenir Magazine for the article "Barbara March & Gwynyth Walsh: Lursa and B'Etor", p. 72 in 1994 and for the Star Trek Communicator, issue 104, October 1995, article "The Klingon Way: B'Etor", p. 50-52. Walsh was also interviewed by David Bassom for the article "Forbidden Thoughts" in the Star Trek Monthly magazine, issue 41, p. 62-63, in 1998 and by Ian Spelling for the articles "Double Trouble" in issue 36 in 1998 and "B'Etor the Devil You Know" in issue 73 in 2000.
Following her appearance in Generations, Walsh appeared on several trading cards, book marks, posters, and standups for display.    In 1994 there was also an action figure of her character from the movie, released by Playmates Toys.  Her costume from Generations was sold at the Christie's auction in New York. 
Together with fellow on-screen sister and Canadian Barbara March, Walsh is a frequent guest at Star Trek related conventions such as Trek Expo 2008 and the Creation Las Vegas Star Trek Conventions 2010 and 2011, also appearing in Klingon makeup and costume.   
Personal & Stage Edit
Walsh was born in 1958 in Winnipeg, Manitoba, Canada and raised in Vancouver, British Columbia. She attended the University of Alberta and graduated with a Bachelor of Fine Arts. Soon after her graduation she started to work in stage plays across Canada and the United States including Shakespeare's "Much Ado About Nothing" for which she received the Drama Logue Award for Best Actress.
Other plays Walsh performed in include "Henry IV", "King Lear", "Death of a Salesman", and "The Tempest" in which she played Prospero and earned a Jessie Award nomination.
Since 2006 she is engaged to Canadian actor and voice artist Chris Britton.
Walsh made her television debut in the 1984 television comedy Pajama Tops with Alan Scarfe and in the television musical Iolanthe. She then appeared in episodes of Adderly (1986, directed by Joseph L. Scanlan), Hot Shots (1986), Diamonds (1988), Night Heat (1988, with Allan Royal), Captain Power and the Soldiers of the Future (1988), War of the Worlds (1988, with Richard Chaves and Ric Sarabia), My Secret Identity (1988, with Derek McGrath), Starting from Scratch (1988), Street Legal (1987 and 1988, with Derek McGrath), Friday the 13th (1989), Alfred Hitchcock Presents (1989), and The Twilight Zone (1989).
She also appeared in the television movies A Child's Christmas in Wales (1987), The Return of Ben Casey (1988, directed by Joseph L. Scanlan), The Christmas Wife (1988), The Challengers (1989), Passion and Paradise (1989, with Mariette Hartley and Michael Sarrazin), Perry Mason: The Case of the Maligned Mobster (1989, with Eric Server and Jeff Austin), The Girl from Mars (1991, with Edward Laurence Albert and Kaj-Erik Eriksen), and My Son Johnny (1991).
In 1989 Walsh played Melanie Hayes in three episodes of the television series L.A. Law, along with Corbin Bernsen, Larry Drake, Jerry Hardin, Dana Sparks, Nancy Vawter, Renee Jones, Jim Jansen, Marco Rodriguez, and Barbara Tarbuck. She also guest starred in Alien Nation (1989, with Gary Graham, Eric Pierpoint, Michele Scarabelli, Ron Fassler, and Tracey Walter), Mom P.I. (1990), It's Garry Shandling's Show (1990, with Paul Willson and Patrick Cronin), MacGyver (1991, with Sonny Surowiec), Beyond Reality (1991), Eerie, Indiana (1992, with Justin Shenkarow, Francis Guinan, and Jason Marsden), Sweating Bullets (1991 and 1992), The Commish (1992, with Kaj-Erik Eriksen), and Matlock (1990 and 1993, with Ray Buktenica, Daniel Roebuck, and directed by Russ Mayberry in the latter episode).
In the 1990s Walsh played supporting roles in several television movies such as Darkness Before Dawn (1993, with Kirsten Dunst, Art Chudabala, Frank Novak, Lindsey Ginter, and Earl Boen), Without a Kiss Goodbye (1993, with David Ogden Stiers), In the Heat of the Night: Give Me Your Life (1994), Shock Treatment (1995), Falling from the Sky: Flight 174 (1995, with Mariette Hartley), The Other Mother: A Moment of Truth Movie (1995, with Deborah May), Justice for Annie: A Moment of Truth Movie (1996), The Limbic Region (1996), Stand Against Fear (1996, directed by Joseph L. Scanlan), The Perfect Mother (1997), Final Descent (1997, with John de Lancie), Zenon: Girl of the 21st Century (1999), and Our Guys: Outrage at Glen Ridge (1999).
Also in the 1990s Walsh guest starred on many popular television series including In the Heat of the NIght (1994, directed by Russ Mayberry), Forever Knight (1994, directed by Allan Kroeker), RoboCop (1994), Melrose Place (1994, with Stanley Kamel, Warren Munson, and Christopher Carroll), Murder, She Wrote (1994, with Patrick Fabian and Anthony Zerbe), One West Waikiki (1995 and 1996, with Julia Nickson), Tracy Tormé's Sliders (1996, with John Rhys-Davies), High Incident (1996 and 1997, with Billy Mayo, Jesse Littlejohn, Scott Alan Smith, and Lisa Vidal), The Newsroom (1997), Millennium (1998, with Megan Gallagher, Terry O'Quinn, and John Pyper-Ferguson), Strange World (1999), and Twice in a Lifetime (1999).
Between 1998 and 2002, Walsh played Dr. Patricia Da Vinci in the Canadian crime series Da Vinci's Inquest  and had a recurring role as Dr. Timmons in four episodes of NYPD Blue (2000-2001, with Gordon Clapp, Erich Anderson, and Michael Buchman Silver).
Other credits include the television movies A Gift of Love: The Daniel Huffman Story (1999), Getting Away with Murder: The JonBenet Ramsey Mystery (2000, with Cliff de Young, Brad Greenquist, Albert Hall, J. Patrick McCormack, Holmes Osborne, James Otis, Margot Rose, and Sharon Schaffer), Ice Angel (2000), Stealing Christmas (2003), Flight 93 (2006, with Jeffrey Nordling), Eight Days to Live (2006, with Brian Markinson), Holiday Wishes (2006), Nightmare (2007), Troglodyte (2008), Her Only Child (2008), and episodes of ER (2000, with Scott Jaeck and Lily Mariye), Tom Stone (2002), Stargate SG-1 (2002), Smallville (2002, with John Glover), Taken (2002, with Matt Frewer, Emily Bergl, Rob LaBelle, and Brian Markinson), The Collector (2005), Masters of Horror (2005), Commander in Chief (2006, with Jasmine Jessica Anthony, Samantha Eggar, William Lucking, Ned Vaughn, and Rick Fitts), Tin Man (2007, with Neal McDonough), and Supernatural (2008, with Mark Rolston).
Further appearances include the television science fiction film Storm Seekers (2009), two episodes of the television mini series Knights of Bloodsteel (2009, with Christopher Lloyd), the television drama One Angry Juror (2010), the television comedy To the Mat (2011), and William Shatner's documentary Get a Life! (2012).
Walsh appeared as Dr. Stevens in the American Horror Story second season episode "Spilt Milk" (2013, with Zachary Quinto, Barbara Tarbuck, and Tom Virtue), in an episode of R.L. Stine's The Haunting Hour (2013), and in the television movie The Christmas Ornament (2013). Further television guest roles include episodes of Continuum (2014, with Rachel Nichols, Tony Amendola, and Brian Markinson), The Lottery (2014), and The Whispers (2015, with Derek Webster, David Andrews, and Alan Ruck) as well as the television movies The Color of Rain (2014), For Better or for Worse (2014), Heavenly Match (2014), A Gift of Miracles (2015), and 'Tis the Season for Love (2015).
More recently, Walsh filmed the television drama Journey Back to Christmas (2016, with Claire Rankin) and recurring roles as the voice of Doris the spider in the television series Beat Bugs (2016) and as Magdalene in Van Helsing (2016).
Walsh made her feature film debut in the 1987 horror film Blue Monkey followed by the romance La bottega dell'orefice (1989, with Ben Cross), the Canadian drama The Portrait (1992, with Barbara March and Alan Scarfe), the thriller The Crush (1993, with on-screen husband Kurtwood Smith), and the thriller Sof Deceit (1994, with Kate Vernon).
In 1997 she was featured in the science fiction movie 2103: The Deadly Wake with Malcolm McDowell as well as in the independent film Crossing Fields. In 2004 she appeared in the video production MXP: Most Xtreme Primate and played Sarah in the short horror film Flush for which she received the Leo Award in the category Short Drama: Best Performance by a Female in 2005.
In 2007 Walsh received another Leo Award nomination for her part as Sidura Abelson in the short film The Sparkle Lite Motel (2006). In 2009, she starred in the short drama No One Knows You Like Your Mother, followed by the thriller Even Lambs Have Teeth (2015), the short comedy A Family of Ghosts (2016), and more recently the comedy Chokeslam (2017).