Katrin Saß, born Ocotber 23, 1956, in Schwerin, already as a school girl accompanied her mother, actress Marga Heiden, to rehearsals, performances and on tour. After finishing 10th grade, she completed a telephone operator's training and afterwards studied at the Rostock drama school for three years. Director Heiner Carow cast her for the leading part in his movie "Bis dass der Tod euch scheidet" ("Until Death Do Us Part"). Her performance as salesgirl Sonja who is strained by the conflicts of her young marriage was a success with critics and moviegoers alike.

After finishing drama school, Saß became a cast member of the Kleist-Theater in Frankfurt (Oder). Besides her theatre work she also played minor parts in TV movies. In 1981, managing director Peter Sodann brought her to the Landestheater Halle where Saß performed in classic roles and contemporary GDR and Soviet drama. Her second leading role in a movie was the part of the single worker Nina Kern, who fights for the custody for her three children, in Herrmann Zschoche's "Bürgschaft für ein Jahr" which became an international success and won Saß best actress and the Silver Bear at the 1982 Berlinale.

Katrin Saß who managed to portray her characters in a more and more differentiated way then played pivotal roles in Roland Gräf's films "Das Haus am Fluss" und "Fallada – Letztes Kapitel" ("Fallada - The Last Chapter", 1988). "Der Traum vom Elch" (1986) was her first movie with director Siegfried Kühn who directed "Heute sterben immer nur die Anderen", one of the last ever DEFA productions, in 1990, the year of the German reunification.

Right after the German reunification Saß mainly worked for TV productions and played minor roles in films of former DEFA directors. From 1994 to 1997, she played Commissar Tanja Voigt in several episodes of the TV crime series "Polizeiruf 110" for ORB in Potsdam. After a severe existential crisis, Saß made a comeback in 1999 in the TV thriller "Sperling und der brennende Arm". Her portrayal of a restaurant owner won Saß a Fernsehpreis. In the same year, Saß also starred in the large-scale production "Klemperer – Ein Leben in Deutschland", a TV mini-series.

Shortly after, Saß was to be seen on the big screen again: she played a supporting role in Andreas Dresen's "Die Polizistin" ("The Policewoman") and then played the title role in Michael Klier's portrait "Heidi M.", a woman struggling with her life who only hesitantly and reluctantly gets back into a relationship with a man. This convincing performance won her Deutscher Filmpreis and Preis der deutschen Filmkritik. Saß also starred in Wolfgang Becker's internationally successful comedy "Good Bye, Lenin!", another X Filme production, about the end of the German Democratic Republic.

Besides her theatre work, Sass has since mainly been seen in TV productions, including the TV series "Mitten im Leben" (2007) and "Dell & Richthoven" (2008), as well as several episodes of "Tatort" and "Der Alte", and the award-winning tragicomedy "Meine verrückte türkische Hochzeit" (2006). On the big screen, Sass has focused on parts in ambitious productions such as Bernd Böhlich's "Mutterseelenallein" ("All Alone", 2005), Christian Wagner's "Warchild" (2006) oder Oskar Roehler's "Lulu & Jimi" (2009).

For her role in "Das letzte Schweigen" ("The Silence", 2010), as a mother whose eleven-year-old daughter falls victim to a sex killer, Sass was nominated for the German Film Critics' Award.

In 2010, Sass took on a leading role as a GDR civil rights activist in Friedemann Fromm's highly acclaimed, multiple award-winning series "Weissensee" (three seasons until 2016). In addition, she continued to appear in television dramas, such as the crook comedy "Heiratsschwindler küsst man nicht" (2012), about a wife who wants to take revenge on her cheating lover. On the big screen, she played the strict director of a retirement home in "Sein letztes Rennen" ("Back on Track", 2013).

Since 2014, Sass has played the lead role of a prosecutor with a criminal record for murder in the crime series "Der Usedom-Krimi," who becomes an amateur investigator after her release from prison. In the series "Block B - Unter Arrest" (2015), she showed an unusually tough side as a brutal and powerful prison inmate. In 2015, Katrin Sass was awarded the European Culture Prize of the Basel cultural foundation "Pro Europa".

In Anna Justice's TV tragicomedy "Harrys Insel" ("Harry's Island", 2017), Sass played the lead role of an unconventional ex-hippie who thwarts retiree Harry's (Wolfgang Stumph) plans to retire in solitude and peace on a Canadian island. In the same year, Umut Dag's TV drama "Das deutsche Kind" premiered at the Hof Film Festival, in which she plays the grandmother of a child who, according to her late mother's will, is supposed to grow up with a neighboring Muslim family. After a supporting role in the streaming series "Dogs of Berlin," Katrin Sass was seen on the big screen in 2019 in Karoline Herfurth's "Sweethearts" as the mother of one of the main characters.  

In between, she continued to investigate as a former prosecutor in several episodes of the ARD series "Der Usedom-Krimi," the most recent of which will be broadcast in November 2021.