Mary Roos (born Rosemarie Schwab on 9 January 1949) is a German singer and actress.
Schwab was born in Bingen. At the age of nine, she recorded her first song "Ja die Dicken sind ja so gemütlich" as Die kleine Rosemarie. It was no major commercial success. In 1958, she also appeared in the film Die Straße. Over the following years she would release many records and she also appeared in many singing competitions. Her first chart success came in 1965, when the single "Geh nicht den Weg" peaked at #36. In 1969, she took part in the Grand Prix RTL International with the song "Die Legende der Liebe". The same year, she reached the single charts again – "Das hat die Welt noch nicht erlebt" peaked at #19. Her first major was achieved in 1970 with the song "Arizona Man". It peaked at #9 in the single charts and remains her only top ten hit to date. The same year, she took part in the German national final for the Eurovision Song Contest for the first time. She was chosen to take part in the last minute – Edina Pop had to withdraw from the competition as she fell ill and Mary Roos was chosen to sing "Bei jedem Kuss" instead. She finished joint second among the six participants; nevertheless, the song was never recorded.