Political organisations
U
| Name | Type | Notes |
|---|---|---|
| Ulster Farmers' Union | Pressure group | |
| Ulster Unionist Council | Party group | |
| Ulster Unionist Labour Association | Pressure group | |
| UNA | International body | |
| Union Defence League | Pressure group | |
| Unionist Association | Party group | |
| Unionist Free Trader | Pressure group | |
| Unionist Labour | Party group | |
| Unionist Workers' League | Pressure group | |
| Union of Democratic Control | Pressure group | |
| Unitarian | Religious | |
| United Empire Trade League | Pressure group | |
| United Free Church | Religious | |
| United Irish League | Miscellaneous | |
| United Kingdom Alliance | Pressure group | |
| United Kingdom Band of Hope Union | Religious | |
| United Kingdom Commercial Travellers' Association | Pressure group | |
| United Law Society | Trade group | |
| United Synagogue | Religious | |
| UPUK Alliance | Party group |