Short answers, pulled from the story.
The Parliament of England passed the Act of Supremacy 1534 on the 3rd of November 1534. This legislation declared King Henry VIII the only supreme head on Earth of the Church of England and severed the tie between the English church and the papacy in Rome.
Henry VIII created the Act of Supremacy 1534 due to a desperate dynastic need to annul his marriage to Catherine of Aragon. Pope Clement VII refused to grant the annulment because the Emperor Charles V held the Pope in his power, prompting Henry to assert independence from the Catholic Church.
Thomas More was convicted of treason and executed by beheading after the Treasons Act 1534 was passed. The act transformed theological disagreement into a capital crime, making it treason to disavow the Act of Supremacy or deprive the king of his dignity.
The first Elizabethan Parliament passed the Act of Supremacy 1558 after Queen Mary I died in November 1558. This new act declared Elizabeth I the Supreme Governor of the Church of England, a title chosen to pacify Catholics and Protestants concerned about a female leader.
The Parliament of Ireland passed the Irish Act of Supremacy 1537 in 1537. This legislation established Henry VIII as the supreme head of the Church of Ireland and mirrored the actions taken in England to extend the English Reformation to the island.
The royal supremacy was extinguished during the British Interregnum from 1649 and was restored in 1660. The Stuart kings used the restored supremacy as a justification for controlling the appointment of bishops.