A favorite player of director Hal Hartley, Karen Sillas has appeared to great effect in a number of his films, notably Trust and Simple Men. Her work in Hartley's films established the blonde, strong-jawed actress as a solid talent with a proclivity for deadpan humor, something she has also exhibited in a variety of film, television, and stage productions including Tom Noonan's What Happened Was..., a darkly humorous date movie that earned Sillas particular praise.

A native of Brooklyn, where she was born June 5, 1965, Sillas studied at the acting conservatory at the State University of New York at Purchase. She got her start in films in the 1980s, making her debut in Hartley's first film, the 1984 short Kid. She and Hartley next collaborated on Trust (1990), which cast Sillas in the supporting role of a sage, no-nonsense abortion clinic nurse. She had a more substantial part in Hartley's Simple Men (1992), playing a lonely cafe owner. Sillas was given her first chance to carry a movie with Tom Noonan's What Happened Was...; her turn as a woman out on a singularly awkward date with a co-worker (Noonan) earned her an Independent Spirit Award nomination, while the film itself received the Grand Jury Prize at the 1994 Sundance Festival.

As a result of her work in What Happened Was..., Sillas landed the starring role of the only female detective in an otherwise male-dominated squad room on the acclaimed TV detective series Under Suspicion. Although the show was eventually cancelled, the actress continued to appear in a number of TV series and independent films, including Hartley's Flirt (1995), Susan Streitfeld's Female Perversions (1996), which cast her as Tilda Swinton's psychiatrist lover, and Sour Grapes (1998), a black comedy which featured her as the girlfriend of a greedy neurologist. Rebecca Flint, All Movie Guide

  Wanted"
- Judas (2005) TV Episode .... Mariah Belichek
- La pistola Y el corazón (2005) TV Episode .... Mariah Belichek
- Shoot to Thrill (2005) TV Episode .... Mariah Belichek
- Click, Click, Boom (2005) TV Episode .... Mariah Belichek
- The Promise of Darkness (2005) TV Episode .... Mariah Belichek
(3 more)
Wanted (2005) (TV) .... Mariah Belichek
"Law & Order: Criminal Intent"
... aka Law & Order: CI (USA: promotional abbreviation)
- Consumed (2004) TV Episode .... Beth Landau
"Without a Trace"
- Legacy (2004) TV Episode .... Martha Stanley
"CSI: Miami"
- Dead Woman Walking (2003) TV Episode .... Belle King
The Other Side (2001) (TV) .... Anna
On the Edge (2001/II) (TV) .... Anna (segment "The Other Side")
"Falcone"
- Pilot (2000) TV Episode .... ADA Diane Gianetti
75 Degrees in July (2000) .... Letty Anderson

Bad Money (1999) .... Jan Wells
As Time Runs Out (1999) (TV) .... Janet Wise
"The Sopranos"
- Nobody Knows Anything (1999) TV Episode .... Debbie
Reach the Rock (1998) .... Donna
"Promised Land"
... aka Home of the Brave
- Vengeance Is Mine: Part 2 (1998) TV Episode .... Sandra Mills
"Touched by an Angel"
- Vengeance Is Mine: Part 1 (1998) TV Episode .... Sandra Mills
Lulu on the Bridge (1998) (uncredited) .... Candy (DVD deleted scene)
Sour Grapes (1998) .... Joan
The Repair Shop (1998)
Lies He Told (1997) (TV) .... Alyson Haywood
Night Sins (1997) (TV) .... Dr. Hannah Garrison
The Beast (1996) (TV) .... Lt. Kathryn Marcus
... aka Peter Benchley's The Beast
Female Perversions (1996) .... Renee
... aka Phantasien einer Frau (Germany)
Flirt (1995/I) .... Doctor Clint
"Under Suspicion" (1994) TV Series .... Det. Rose "Phil" Phillips (1994-1995)
"Law & Order"
... aka Law & Order Prime (USA: informal title)
- Big Bang (1994) TV Episode .... Cynthia Thomas
What Happened Was... (1994) .... Jackie Marsh
Risk (1994) .... Maya
Trip nach Tunis (1993)
Simple Men (1992) .... Kate
... aka Uomini semplici (Italy)
Liebestraum (1991) .... Nurse #3
"Monsters"
- Bug House (1990) TV Episode
Trust (1990) .... Nurse Paine

The Cartographer's Girlfriend (1987)
Kid (1984) .... Patsy