The Bulgarian Greek Catholic Church is a Byzantine Rite sui juris particular Church in full union with the Roman Catholic Church.

The Greek Catholic Church consists of the Eastern Catholic Churches which follow the Byzantine (Constantinopolitan) liturgical tradition and are thus in full communion with the Bishop of Rome, the Pope.

The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with more than one billion members. Led by the Pope, it defines its mission as spreading the Gospel of Jesus Christ, administering the sacraments and exercising charity.

The Catholic Church is among the oldest institutions in the world and has played a prominent role in the history of Western civilisation. It teaches that it is the one true Church founded by Jesus Christ, that its bishops are the successors of Christ's apostles and that the Pope is the sole successor to Saint Peter.

Catholic doctrine maintains that the Church is infallible when it dogmatically teaches a doctrine of faith or morals. Catholic worship is centred on the Eucharist in which the Church teaches that bread and wine become the body and blood of Christ.

The Church holds the Blessed Virgin Mary in special regard. Catholic beliefs concerning Mary include her Immaculate Conception without original sin, her Motherhood of God and her bodily Assumption into Heaven at the end of her earthly life.

Joanna of Italy (Bulgarian: Йоанна Савойска, Italian: Giovanna Elisabetta Antonia Romana Maria) (13 November 1907 – 26 February 2000) was the last Tsaritsa of Bulgaria.

Giovanna was born in Rome, the third daughter and fourth child of King Victor Emmanuel III of Italy and Queen Elena, former Princess of Montenegro. She was raised in the Villa Savoia and from a young age was aware of her aim in life: to further the House of Savoy's dynastic aspirations through marriage. Upon her christening into the Catholic faith, she was given the names Giovanna Elisabetta Antonia Romana Maria. Her older brother was the future Italian king Umberto II of Italy.

Although it would eventually prove to be of no assistance to Italy, Giovanna duly married Tsar Boris III of Bulgaria in Assisi in October 1930, in a Roman Catholic ceremony, attended by Italian dictator Benito Mussolini. Bulgarians deemed her a good match, partly because of her mother's native Slavic ethnicity. At a second ceremony in Sofia, Bulgaria, Giovanna (who herself was daughter of a Roman Catholic father and a born Orthodox mother) was married in an Eastern Orthodox Church ceremony, bringing her into conflict with the Roman Catholic Church. Giovanna adopted the Bulgarian version of her name, Ioanna. Giovanna knew the Pope's Apostolic Visitor to Bulgaria, Archbishop Angelo Roncalli, the future Pope John XXIII who was able to help her. She and Boris had two children: Marie-Louise of Bulgaria, born in January 1933, and then the future Simeon II of Bulgaria in 1937.