Marina Soulakiotou,  also known either to her followers as Mariam of Keratea, or in contemporary media pejoratively as "Mother Rasputin", was a Greek Old Calendarist Eastern Orthodox abbess who was found guilty of numerous counts of serial murder, fraud and other crimes, which public prosecutors of the Kingdom of Greece alleged she committed against both laypeople and other nuns in her abbey between 1939 and her arrest in December 1950.