Jovan Oliver GrÃÂinià(; ca. 1310âÂÂ1356) was a magnate of the Serbian Emperor Duà ¡an the Mighty (r. 1331âÂÂ1355), holding the titles of sebastokrator and despotes, and the rank of "great voivode", showing his prominence and status as one of the most important nobles of Duà ¡an. Oliver supported Duà ¡an in the succession war against his father, and was one of the supreme generals in the southern military expeditions (Macedonia, Thessaly). His province included OvÃÂe Pole and the left bank of the Vardar. After the death of Emperor Duà ¡an, there are no more mentions of Oliver. During the fall of the Serbian Empire, his lands were held by the DejanoviÃÂi.
Jovan was the son a vlastelin GrÃÂin (ÃÂÃÂÃÂøý, "Greek") who had lands in some part of the Serbian Kingdom.
Jovan is referred to in a Ragusan source as Oliver GrÃÂiniÃÂ, and his knowledge of Greek lends support to the notion of a Greek origin. He ruled his domain, in modern-day North Macedonia, as a semi-independent prince, acknowledging Duà ¡an's suzerainty but not subordinate to him. He probably had supported Duà ¡an's overthrow of his father, King Uroà ¡ III, in 1331, and after the death of his first wife, Karavida, in 1336, he married Maria Palaiologina, Duà ¡an's stepmother. His second wife is depicted in a 1349 fresco and described as "Maria Lyverina" or "Ana Maria Liverina" at Lesnovo. There is considerable scholarly debate as to when Jovan Oliver acquired his domains, i.e. whether he held them before Duà ¡an's accession, whether they were granted to him by Duà ¡an as a reward for his support, or whether he gained them as a result of his marriage to Maria.
At any rate, he was one of the most powerful nobles under Duà ¡an, and exercised considerable influence over him, as evidenced in the negotiations in July 1342 which led to the decision to support John VI Kantakouzenos in the Byzantine civil war of 1341âÂÂ1347, in exchange for which he hoped to marry his daughter to Manuel Kantakouzenos. He was also active in the 1334 war with the Byzantine Empire, and was present during the subsequent peace negotiations together with Vratko NemanjiÃÂ, when Jovan was probably named despotes by Andronikos III Palaiologos. With the death of Hrelja in late 1342, when the latter's domain was split between Jovan Oliver and Duà ¡an, he was able to further expand his lands, including the important towns of à  tip and Strumica.
In 1341, imitating the Serbian kings, he built the Eastern Orthodox Lesnovo monastery as his endowment. Jovan Oliver outlived Duà ¡an, but after his death, his sons were unable to assert themselves: possibly opposed by a coalition of other nobles, they failed to acquire any positions of importance, and most of their father's lands were taken over by Constantine and John, the sons of sebastokrator Dejan Dragaà ¡ of Kumanovo.
He had 7 children: