According to Manetho, Egypt's 7th dynasty had 70 pharaohs in 70 days. Much later on King Louis XIX of France would reign for 20 minutes in 1830…

Here's the timeline of events for those who want to know:
-Elected President Fernando de la Rúa: December 10th 1999 to December 21st 2001, stepped down.
-Senator for the Province of Misiones Ramón Puerta: December 21st to December 23rd, provisional head of the executive power, never swore oath therefore not officially President.
-Governor of the Province of San Luís Adolfo Rodríguez Saá: December 23rd to December 30th 2001, stepped down.
-President of the Chamber of Deputies Eduardo Camaño: December 30th 2001 to January 2nd 2002, provisional head of the executive power, never swore oath therefore not officially President.
-Senator for the Province of Buenos Aires Eduardo Duhalde: January 2nd 2002 to May 25th 2003, remained in the seat officially until new elections were called which took place earlier than planned on April 27th of 2003.