Monika Griefahn (born 3 October 1954 in Muelheim-Ruhr, Germany) is the co-founder of Greenpeace Germany and a German politician of the SPD.
She was a member of the German Parliament (1998–2009), functioning as an expert on culture and the media as well as foreign (cultural) policy.
From 1990 to 1998 she was the Minister of the Environment in the State of Lower Saxony.
From 1980 to 1990 she was an activist in the environmental organization Greenpeace and the first woman on the international board of Greenpeace (1984–1990).