Derry | Tyrone GAA | Kerry GAA | GAA | Donegal GAA | Dublin GAA | Derry City F.C. | Meath GAA | Mayo GAA | Derry Irvine, Baron Irvine of Lairg | Derry City | Monaghan GAA | Tipperary GAA | Kilmurry Ibrickane GAA | Derry, New Hampshire | Cork GAA | City of Derry Airport | Armagh GAA | St Josephs Doora-Barefield GAA | Siege of Derry | Galway GAA | Free Derry | Derry O'Sullivan | Derry Irvine | Waterford GAA | St Vincents GAA | St. Martin's GAA | St Laurence's GAA | Rathnure GAA | Rathkenny GAA |
He played for Derry in the 1980s and 1990s and was part of the county's 1993 All-Ireland Championship winning side, starting at left half forward.
Peter McGinnity was the outstanding player of the under-21 team which reached two All Ireland finals and defeated Derry and Tyrone to reach the 1982 Ulster final, Despite a Peter McGinnity goal that put them in the lead with 20 minutes remaining, they lost 0-10 to 1-4 to Armagh.
While young, Cassidy's childhood football heroes were Derry's Anthony Tohill, Seán Óg de Paor of Galway and Donegal's Anthony Molloy.