María Fabiana Ríos (born March 31, 1964 in Rosario, Santa Fe) is an Argentine politician of the party Partido Social Patagónico ("Patagonian Social Party").
She was the governor of the province of Tierra del Fuego from December 17, 2007 to December 10, 2015.
She was first elected with the support of the party ARI (Afirmación para una República de Iguales, "Support for an Egalitarian Republic"), but she left it in 2010 and created her own party, with which she was re-elected.
She was the only female governor in Argentina, until the election of Lucia Corpacci of Catamarca Province, currently serving.
She was succeeded in office by another woman, Rosana Bertone.
Ríos was elected governor on June 24, 2007.
She is the first woman to be elected governor of an Argentine province and the first woman governor of Tierra del Fuego Province.
Prior to that she was a National Deputy.Ríos graduated as a pharmacist from the National University of Rosario.
She moved to Tierra del Fuego, a scarcely populated province on the southern end of Argentina, at the age of 23, and married Gustavo Longui, with whom she had two daughters.
She occupied several important posts in the healthcare administration of the city of Río Grande.