Who are the Old Catholics?

[Melquita]

The “Old Catholics” seem to come up a lot in ecumenical literature as a schismatic group whose bishops have helpfully consecrated every living Anglican bishop, as well as hundreds of Lutheran and Methodist bishops, not to mention bishops from assorted and sundry conservative sedevacantist and liberal Catholic splinter groups. Yet I can find no information about how big their church actually is, or what beliefs they profess to hold. The one website they seem to operate lists only about a dozen bishops, which if true must make them just about the busiest people in all of Christendom. Is there actually a community of believing “Old Catholics”, or are they just a handful of renegade bishops who hire themselves out to anyone desirous of holy orders?

 

[Dale_M]

Yes, there is an ecclesial community of Old Catholics, at least in Europe.

Its claims to apostolic succession lies in the Jansenist schism. For many years, the Jansenists refused to accept a bishop appointed by Rome.
Original Catholic Encyclopedia:

The conflict lasted a long time, during which the episcopal functions were not fulfilled. In 1723 the Chapter of Utrecht i.e. a group of seven or eight priests who assumed this name and quality in order to put an end to a precarious and painful situation, elected, on its own authority, as archbishop of the same city, one of its members, Cornelius Steenhoven, who then held the office of vicar-general. This election was not canonical, and was not approved by the pope. Steenhoven nevertheless had the audacity to get himself consecrated by Varlet, a former missionary bishop and coadjutor Bishop of Babylon, who was at that time suspended, interdicted, and excommunicated. He thus consummated the schism; interdicted likewise and excommunicated, he died in 1725. Those who had elected him transferred their support to Barchman Wuitiers, who had recourse to the same consecrator. The unhappy Varlet lived long enough to administer the episcopal unction to two successors of Barchman, van der Croon and Meindarts. The sole survivor of this sorry line, Meindarts, ran the risk of seeing his dignity become extinct with himself. To prevent this, the Dioceses of Haarlem (1742) and Deventer (1757) were created, and became suffragans of Utrecht. But Rome always refused to ratify these outrageously irregular acts, invariably replying to the notification of each election with a declaration of nullification and a sentence of excommunication against those elected and their adherents.

oce.catholic.com/index.php?title=Jansenius_and_Jansenism

After Vatican I, groups of Catholics in Germany, Switzerland and the Netherlands were angry over the issue of papal of infallibility, and broke with Rome, Because no bishops joined their schism, these “Old Catholics” , as they called themselves, approached the Utrecht breakaway church to have bishops validly consecrated, preserving apostolic succession. The resulting cooperation was the Union of Utrecht, from which one branch is now called the Union of Utrecht of the Old Catholic Churches.
utrechter-union.org/english/history001.htm

The Union of Utrecht has apparently added, and sometimes spun off, other Catholic denominations, but I don’t know those histories. Apparently some of them are markedly different in beliefs and practices compared to the Catholic Church we all know and love.