The Nationwide Group Staff Union (NGSU) is an independent trade union in the United Kingdom. It has a membership of over 12,000 and represents workers within the Nationwide Building Society and its associated companies.
The NGSU was formed in 1990 by the merger of Anglia Building Society Staff Association and Nationwide Building Society Staff Association. The Portman Group Staff Association (PGSA) transferred engagements to NGSU in 2008. It is affiliated to the Trades Union Congress.
The union absorbed the Staff Union Dunfermline Building Society on 1 January 2011, and One Union of Regional Staff on 1 September.