King Henry VIII separated from the Roman Catholic Church and founded the Anglican Church (Church of England) because Pope Clement VII refused to annul his marriage to Catherine of Aragon. Catherine had not borne Henry an heir, to Henry's dismay. He wanted to divorce Catherine so he could marry Anne Boleyn, Catherine's lady-in-waiting.
Since Clement would not accede to Henry's wishes for an annulment, the king made the extraordinary decision to separate from the Catholic Church and declare himself the "Supreme Head in Earth of the Church of England." Despite breaking with the Catholic Church, Henry retained mostly Catholic practices, although he dissolved the Catholic monasteries, convents, and friaries located within his kingdom.
Once separated from the Catholic Church, Henry was able to divorce Catherine and marry Anne Boleyn. He would later execute Anne and have four more subsequent marriages.