Ann Louise Gilligan (27 July 1945 – 15 June 2017) was an Irish theologian who taught at Saint Patrick's College, Drumcondra (part of Dublin City University). A former nun, she was the wife of Katherine Zappone. In "Zappone and Gilligan v. Revenue Commissioners" (2006), they unsuccessfully sought recognition of their Canadian marriage. Despite failing in the courts, Gilligan was a leading campaigner in Ireland's 2015 same-sex marriage referendum, and ultimately succeeded in having her marriage recognised in Irish law before her death in 2017.