St. Jacob Baradeaus, venerated in the Syriac and Syriac-associated Orthodox Churches on July 29th (very close to my birthday), was a bishop consecrated for Edessa, but was also entrusted by the non-Chalcedonian patriarchs and bishops, who were jailed in Constantinople by the emperor Justinian, to travel all over the empire to consecrate clergy on their behalf. So in essence, even though he was bishop of Edessa, he was essentially a crucial "ordainer" for the whole non-Chalcedonian Church. St. Theodosius, Coptic Pope of Alexandria himself entrusted St. Jacob Baradeaus with the task of ordaining bishops and priests in his seat. This was at a time when the non-Chalcedonian clergy were being persecuted and dwindling fast. St. Jacob Baradeaus bravely traveled all over, and have said to have ordained about 8000 clergy in the process, keeping the Oriental Orthodox Church strong, from Persia to Arabia to Asia Minor to Syria to Egypt to islands in the Mediterranean. He also ordained two anti-Chalcedonian patriarchs back to back for Antioch, which later on stuck with the Syrian Church that they would be called "Jacobite" by Chalcedonians, considering from then on, it was this saint who lead the ordination of the patriarchate of Antioch. He was perhaps the most wanted man in the empire for doing this, had considerable authority over the churches, and was able to evade capture throughout his decades of service.
Because of his ordination of a lot of Coptic bishops, the Coptic Church at times were also called Jacobite, although the name is more popularly used for Syriacs.
He left a few letters floating around, although I don't think they're translated. He is said to have also written a liturgy as well.