William Walsh, (7 November 1804 – 11 August 1858), was an archbishop of the Roman Catholic Archdiocese of Halifax, born in Waterford, Co. Waterford, Republic of Ireland and died in Halifax, Nova Scotia.
Walsh became bishop of Halifax in 1845 and in 1852, was appointed archbishop of an expanded ecclesiastical province of Nova Scotia, also designated as Halifax. He became the first archbishop in British North America outside Quebec.