Protestantism
Several countries have established their national churches, linking the ecclesiastical structure with the state. Jurisdictions where a Protestant denomination has been established as a state religion include several Nordic countries; Denmark (including Greenland), the Faroe Islands (its church being independent since 2007), Iceland and Norway have established Evangelical Lutheran churches. Tuvalu has the only established church in Reformed tradition in the world, while Tonga—in the Methodist tradition. The Church of England is the officially established religious institution in England, and also the Mother Church of the worldwide Anglican Communion.

Q: Who is the head church of the Anglican Communion?
The Church of England