[1] Koop began her career as a stage actress at the Endla Theatre in Pärnu in 1979, an engagement that lasted until 1994. Notable roles at the Endla Teatre have been in works by: Dagmar Normet, Juhan Smuul, William Shakespeare, Paul-Eerik Rummo, August Kitzberg, Agatha Christie, Stephen Poliakoff, Hugo Raudsepp, Franz von Pocci, Brian Friel, Jean Anouilh, Claude Magnier, and Tony Roper.
[2] The following year, she had a more significant role as Miia in the Valentin Kuik directed television film Teaduse ohver.
[3] In 1987, she appeared in two prominent roles in television films: as Käo Linda in the Eesti Televisioon (ETV) historical epic Tants aurukatla ümber, directed by Peeter Simm and written by Mats Traat, and as Knuters Minna in the Olav Neuland directed historical drama Näkimadalad; an adaptation of the Herman Sergo penned novel of the same name.
[3] During the 1990s, Koop appeared in several more films: As Marta in the 1990 Arvo Iho directed Tallinnfilm drama Ainult hulludele ehk halastajaõde and as the character Silin's wife in the 1999 Peeter Simm directed drama Sellised kolm lugu: Aida for Lege Artis Film.
In 2017, Koop returned to film in two roles: as the apparition of the character Hans' mother in the Rainer Sarnet directed dark fantasy-drama November, and a small role as a member of a therapy group in the Andres Maimik and Katrin Maimik directed comedy film Minu näoga onu.