There are currently two non-member observer states:
Although the UN Charter and the General Assembly Rules of Procedure have no provisions related to granting observer status, the General Assembly may grant non-member states, international organizations and other entities observer status.
The Holy See is currently a non-member observer state of the UN General Assembly. The Holy See "became a Permanent Observer State at the United Nations on 6 April 1964" according to A/RES/58/314.
The State of Palestine is currently a non-member observer state of the UN General Assembly.
General Assembly resolution A/RES/ES-10/23 of 10 May 2024 concerns the participation of the State of Palestine "in the sessions and work of the General Assembly and the international conferences convened under the auspices of the Assembly or other organs of the United Nations, as well as in United Nations conferences".
In its preamble, the resolution cites earlier resolutions on the status of Palestine in the General Assembly:
Related decisions of other UN System bodies include:
The December 1952 volume of Permanent Missions and Delegations to the United Nations (page 125) lists the following “Non-Member Nations Maintaining Permanent Observers Offices at Headquarters”; all have become UN Member States since that time:
Other states may have maintained permanent observers offices at other times. Consult the Permanent Mission Blue Book to see the observers at any given time.