South Sudan became an independent nation after a prolonged conflict and a referendum where the majority voted for independence. It was recognized by the United Nations shortly after.
Kosovo declared independence from Serbia after years of conflict and international intervention. While it is recognized by over 100 UN member states, it is not universally recognized and has not been admitted to the United Nations.
Montenegro became independent following a referendum in which a majority voted for independence, dissolving the State Union of Serbia and Montenegro.
Serbia became an independent nation after Montenegro voted to secede and form its own country, leading to the dissolution of the State Union of Serbia and Montenegro.
East Timor declared independence from Indonesia after a UN-supervised referendum in 1999 and a subsequent period of UN administration.