Wikipedia
Lucius Septimius Udaynath, Latinized as Odaenathus ( / ; / ; 220–267), was the founder king ( Mlk) of the Palmyrene Kingdom centered at the city of Palmyra, Syria. He lifted his city from the position of a regional center subordinate to Rome into the supreme power in the East. Odaenathus was born into an aristocratic Palmyrene family who had received Roman citizenship in the 190s under the Severan dynasty. He was the son of Hairan the descendant of Nasor. The circumstances surrounding his rise are ambiguous; he became the lord (Ras) of the city, a position created for him, as early as the 240s and by 258, he was styled a consularis, indicating a high status in the Roman Empire.
The defeat and captivity of emperor Valerian at the hands of the Persian Sassanian monarch Shapur I in 260 left the eastern Roman provinces largely at the mercy of the Persians. Odaenathus stayed on the side of Rome; assuming the title of king, he led the Palmyrene army and fell upon the Persians before they could cross the Euphrates to the eastern bank, and inflicted upon them a considerable defeat. Then, Odaenathus took the side of emperor Gallienus, the son and successor of Valerian, who was facing the usurpation of Fulvius Macrianus. The rebel declared his sons emperors, leaving one in Syria and taking the other with him to Europe. Odaenathus attacked the remaining usurper and quelled the rebellion. He was rewarded many exceptional titles by the emperor who formalized his self-established position in the East. In reality, the emperor could have done little but to accept the declared nominal loyalty of Odaenathus.
In a series of rapid and successful campaigns starting in 262, he crossed the Euphrates and recovered Carrhae and Nisibis. He then took the offensive to the heartland of Persia, and arrived at the walls of its capital Ctesiphon. The city withstood the short siege but Odaenathus reclaimed the entirety of Roman lands occupied by the Persians since the beginning of their invasions in 252. Odaenathus celebrated his victories and declared himself King of Kings, crowning his son Hairan I as co-king. By 263, Odaenathus was in effective control of the Levant, Mesopotamia and Anatolia's eastern region.
Odaenathus observed all due formalities towards the emperor, but in practice ruled as an independent monarch. In 266, the king launched a second invasion of Persia but had to abandon the campaign and head north to Bithynia to repel the attacks of Germanic riders besieging the city of Heraclea Pontica. He was assassinated in 267 during or immediately after the Anatolian campaign, together with Hairan. The identities of the perpetrator or the instigator are unknown and many stories, accusations and speculations exist in ancient sources. He was succeeded by his son Vaballathus under the regency of his widow Zenobia, who used the power established by Odaenathus to forge the Palmyrene Empire in 270.