Mari Elina Knihtilä (born June 6, 1971) is a Finnish actress.
Knihtilä has worked for several Finnish theatres, such as the Finnish National Theatre and Q-teatteri, while also having appeared in films and on television. She has received two Jussi Awards; one for a supporting role in the 2008 Heikki Kujanpää film Putoavia enkeleitä and another for a leading role in the 2011 Zaida Bergroth film Hyvä poika. Some of her television work include the comic roles in Läpiveto, Vedetään hatusta and the first season of Putous.
Knihtilä is cohabiting with actor Tommi Korpela. Together they have a son.