Chester Olszewski from the United States is one of the least known of the modern alternative popes. He was a cradle Catholic who converted to the Episcopalian Church and became a priest. From 1974, he served as a priest in Eddystone, Pennsylvania. In the following year, he became convinced that a statue of the Sacred Heart Christ, owned by a Catholic woman, Anne Poore, bled and bore the stigmata. Olszewski brought the statue to church, where he made it the central devotion.
Shortly thereafter, Olszewski and Poore claimed to be divinely chosen to restore the traditional Catholic faith; God had converted them to Catholicism. In order to re-establish the true Catholic Church, Olszewski needed to become a bishop and he soon found an independent bishop who provided him with the much sought-after apostolic succession.
On 31 May 1977, Olszewski proclaimed himself Pope Chriszekiel Elias at a ceremony in St. Lukes’s Episcopal Church in Eddystone, alleging that God himself had elected him and provided him with his new name. Later he began to call himself Peter II, the last pope in history.
Here you can read my article on the Pope of Eddystone, Anne Poore and their church. It’s the first more extensive study on the subject.