He was born around 1345. He died on the 6th October 1397 in the Ottoman prison. His body was transferred by his brother Nikolaos Radochnas (Monk Gerasim) to the Mount Athos. He appears as a gospodinь in the slavic sources and as a dominus in the latin sources. He administered the region of Kastoria and Ōhrid according the Byzantine historians Ducas and Laonikos Chalkokondyles (ἐπὶ δὲ τῇ ἑτέρᾳ Βοῦλκον τὸν τοῦ Πράγκου τοῦ Μλαδένεω υἱόν, Καστορίας τε καὶ Ὀχρίδος τῆς ἐν Μακεδονίᾳ ἡγεμόνος; καὶ τὴν ἄλλην τὴν εἶχε δοσμένη τοῦ ἀφεντὸς τοῦ Μπούλκου ὁποὺ ὥριζε τὴν Καστορία καὶ τὴν Ὄχριδα). Laonikos Chalkokondyles calls him wrongly Ἐλεάζαρος and relates about the lands by the Danube as his dwelling place (τὰ μέντοι περὶ τὸν Ἴστρον Βούλκῳ τῷ Ἐλεαζάρῳ τοῦ Πράγκου ἐπέτρεψε). He controlled the larger part of today’s Kosovo. His dominion reached the eastern parts of Raška, the Polimlje in Montenegro and since 1376/1377 Skopje in the east. After the death of Đurađ I Balšić (13th January 1378) he seized the town of Prizren, Peć and the area of Metohija. He minted his own coins and issued charters. He was the son of Prankos Mladenes (ja Grьgurь i bratь mi Vlьkь, synove velikago sevastokratora Bran’ka gospodina že gradu Ohridu). He had two brothers (Nikolaos Radochnas, Grьgurь) and a sister (Theodora). He was married Mara, the daughter of the Serbian Prince Lazar Hrebeljanović, since 1371. They had together three sons (Georgios Bulkos [Đurađ Branković] - ἦν γὰρ Γεώργιος, υἱὸς Βούλκου καὶ γαμβρὸς Λαζάρου, Prankos Bunko [Lazar Branković], Grьgurь [† 1408]). He and his brother Grьgurь gave Nikolaos Radochnas in 1365 the permission to donate the patrimonial church of Saint Archangel with three villages Trstenik, Bežanići, Tušilo and the selište Hudine to the Hilandar Monastery. He added between 1372 and 1396 the villages Banica, Vrьbovьcь, Štučince, Mučivarě near Trьstenik to the endowment of his brother for the Hilandar Monastery (Po sem’ že jaa blagočьsitivi Vlьkь, synь velikago sevastokratora Branьka raspaljaemь božьstvnyim želanïem velikuju věru i ljubovь iměje kь svetěi matery Hrista moego, priložihь domu ei čьstiomu monastiru bišerečen’nye lavry Hilandaru sela priležeštaa Trьsteniku: Banicu, Vrьbovьcь, Štučince, Mučivarě, sь vsěmi megjami i pravinami i sь ōttěsy selь těhь). He was a benefactor of the Kutlumus Monastery on the Mount Athos since 1370. He granted between 1376 and 1377 at the request of the Monk Gerasim, his brother, the Monastery of Saint George-Gorg near Skopje with all possessions to the Hilandar Monastery (Azь, rabь Hristu Vlьkь, vьspominaju vь sьvědenije vsemь, kako pride brat mi Gerasimь poslanijemь monastirьskimь Svetije Gori Athōna, Svetije Bogorodice Hilandarьskije igumnōmь i vsega sьbora hilandarьskoga, i prosiše mi keliju u Skopju, ponježe ne imahu priběžišta ni kelije u Skopiju. I videvь nihь usrьdije i prošenije, i dah monastirь Svetago Geōrьgija s metohōmь i sь seli i sь vsemi pravinami gde se nahodi metohь Svetago Geōrgija ili u gradu ili na dvoru što jestь Svetago Geōrgija, vse priložihь Hilandaru). He is mentioned as a addressee of the embassy sent by the Ragusan republic in 1380 regarding the release of two citizens of Dubrovnik. He confirmed on the 20th January 1387 the privileges and rights of the Ragusan republic concerning the representation of the citizens of town Dubrovnik in the court assembly. He asked in August 1388 the representatives of the Ragusan republic to clear the old debt and to pay the new Tribute of Ston to the Monks in Jerusalem. He participated in the battle of Kosovo along with his father-in-law Lazar and the Bosnian King Tvrtko I. in 1389. The folk epic poetry portrays him in a bad light as a traitor. The fact is that he withdrew his troops from the battlefield. Between 1389 and 1396 he confirmed the privileges of the Ragusan republic. The Ottomans captured in 1391/1392 Skopje. Bulkos was forced by them to become their vassal. He exempted the Hilandar Monastery from paying the tax to the Ottomans on 21th November 1392. The Venetian republic granted him on 9th April 1394 the citizenship. His Čelnik Smilь deposited gold and silver for Bulkos at Dubrovnik in January 1395. He was captured and imprisoned by the Ottomans not long after the battle of Nicopolis. He is portrayed on the western facade of the chapel of Saint George in the Church of the Holy Mother of God Peribleptos at Ōhrid. There is an inscription next to his image (VELIK...GNБ VLБKБ SNБ SEVASTOKRATORA BRANKA). He commisioned a slavic translation of the chronicle of Georgios Monachos (Hamartolos) in 1387 (Pisa se povelěnyjemь gospodina Vlьka).