Mary Coustas (Greek: Μαρία Κούστας; born 16 September 1964) is an Australian actress, comedian and television personality and writer. Originally from Melbourne, Coustas often performs as the character "Effie", a stereotypical second-generation Greek Australian prone to malapropisms. She completed a Bachelor of Arts at Deakin University in Melbourne, majoring in performing arts and sub-majoring in journalism.

Coustas won the Logie Award for Most Popular Comedy Personality in 1993.