Despite growing awareness of the importance of the role of Non-governmental Organisations (NGOs) in monitoring international human rights law, there is as yet little analysis of the heterogeneous nature of NGOs and of the relationships between NGOs engaging with the United Nations (UN). This socio-legal analysis was drawn from 26 interviews with key stakeholders across the UN, Governments and NGOs. The article analyses, problematises and maps the NGO role, presenting a taxonomy with six categories of NGOs engaging with UN human rights bodies - international facilitative, gatekeeper, imperialist, domestic self-sufficient, domestic dependent and Governmental Non-governmental Organisations (GONGOs). It also considers the role of National Human Rights Institutions in engaging with the UN, vis-à-vis the NGO role. A preferred NGO model of engagement according to those in the UN receiving NGO reports is presented. The article concludes that NGOs play a pragmatic role in addressing limitations of the UN human rights system, and a normative role in contributing to global democratisation and governance.