(written from a Production point of view)
Sierra Pecheur (born 20 September 1938; age 79) is the actress who played Sub-Commander Selok in disguise as Vulcan ambassador T'Pel, in the Star Trek: The Next Generation fourth season episode "Data's Day" in 1990.
Prior to her appearance on TNG, Pecheur co-starred with future Star Trek: Enterprise actor Scott Bakula and Dean Stockwell and fellow TNG guest performers Susan Diol and Norman Large in a 1990 episode of Quantum Leap entitled "M.I.A. – April 1, 1969". Her other television appearances include a 1982 episode of Hill Street Blues (working alongside Barbara Bosson and James B. Sikking), a 1996 episode of NYPD Blue (with Gordon Clapp, Sharon Lawrence, Neal McDonough, and Leland Orser), and such television movies as Wes Craven's Summer of Fear (1978), Friendly Fire (1979, with Phillip Richard Allen and Warren Munson), The Oklahoma City Dolls (1981, with Robert Hooks and David Huddleston), Ghost Dancing (1983, with Bruce Davison, Bill Erwin, and Richard Lineback), The Child Is Mine (1985, with Chris Sarandon), The Betty Ford Story (1987, with Brian McNamara, Eric Menyuk, Kenneth Tigar, and Concetta Tomei), In the Best Interest of the Child (1990, with Ed Begley, Jr. and Kenneth Tigar), A Killer Among Us (1990, with Richard Riehle and Dwight Schultz), and And the Band Played On (1993, with Christopher Carroll, Reg E. Cathey, David Clennon, James Greene, Thomas Kopache, Lawrence Monoson, Saul Rubinek).
She can also be seen in a number of feature films, beginning with Robert Altman's 1977 drama 3 Women, co-starring TOS guest actor Robert Fortier. She later appeared in two thrillers in the 1990s featuring major Star Trek performers: 1993's Kalifornia, which starred Michelle Forbes; and 1996's Eye for an Eye, which featured Armin Shimerman and Natalia Nogulich. Her other film credits include Clint Eastwood's Bronco Billy in 1980, the Western drama Hard Country in 1981 (with the aforementioned Richard Lineback), and the comedy What Women Want in 2000.
Among her last known acting work are an episode of Touched by an Angel (2000) and the short drama Katherine (2002). Today, Pecheur is working fulltime as sculptor, painter, and artist in the Los Angeles area.