Mary Boyle (born 14 June 1970)[1][2][3] was a six-year-old Irish girl who disappeared on the County Donegal-County Fermanagh border on 18 March 1977.

Mary Boyle was last seen at 3:30pm on 18 March 1977 near her grandparents' rural farm in Cashelard, near Ballyshannon, County Donegal.

[14] Over the intervening years, the performer Margo, a friend of and relation to the family, has funded searches on the surrounding hillsides in an effort to try and locate Boyle's body.

[16] The investigation into Boyle's disappearance has attracted some publicity because of allegations of political interference which centred around the accusation that a politician phoned the Gardaí and told them to not question or detain their main suspect.

"[17] The length of time that Boyle has been missing, and allegations of official involvement, led The Guardian to label the case "Ireland's Madeleine McCann.

"[18] Boyle's disappearance is now the longest-running missing child case in modern Irish history,[19] and despite the publicity it attracts, it has not been debated in the Dáil.

The protest was intended to pressure the coroner to hold an inquest into Boyle's death which would allow key witnesses to be interviewed on public record for the first time.

[22] In 2016, controversial media personality Gemma O'Doherty produced a documentary titled Mary Boyle: The Untold Story,[23] which explores several possible causes for her disappearance.

[30] Robert Black, a Scottish serial killer of children, was also proposed as a suspect when it was revealed that he was a cross-border truck driver who often visited County Donegal as part of his job and could have been in the area at the time of Boyle's disappearance.