While some people make a name for themselves, in the case of Og, it may be that the name created the person.

Deuteronomy 3.11 describes King Og of Bashan as ‘the last of the remnant of the Rephaim’ and notes that he is buried in a sarcophagus nine by four cubits in size (13 1/2 by 6 feet). Deuteronomy 1.4 describes King Og as reigning in two cities, Ashteroth and Edrei. In addition, a Ugaritic text from about 1200 B.C. (KTU 1.108) states that another member of the Rephaim (or as they said in Ugaritic, a member of the Rapiˀuma) reigned at Ashteroth and Edrei (or Athtarat and Hedrey). Again, an early fifth-century B.C. tomb inscription from the Phoenician city of Byblos (Byblos 13) summons ‘the Og’ against anybody who would disturb the dead person’s remains.

Gregorio del Olmo Lete follows a fairly widespread understanding when he posits a three-stage development in the traditions about Og: 1. a ‘mythical ideological framework’ was developed at Ugarit concerning the Rephaim; 2. a ‘historical’ record was composed in the Hebrew Bible; and 3. a mythological transformation of the historical Og took place in Phoenicia.

But a couple of factors suggest, to the contrary, that the purportedly real King Og of Deut. 3 was a development from the general title ‘og’. First, the only etymology of ‘Og’ which makes sense of his association with the warriors of the Rephaim is, as Chaim Rabin suggested, something similar to the South Semitic ǵwg, meaning ‘man’ or ‘man of valour’. Thus, ‘Og’ is not a personal name but a title of a Canaanite king. It is similar to other titles of the Ugaritic and Canaanite kings which emphasise their manhood par excellence, and thus their strength and military prowess: e.g., ish, amēlu, mt (Del Olmo Lete, ‘Los nombres “divinos”‘, 257-66). Second, the Phoenician tomb inscription Byblos 13 has a definite article before ‘Og’, making its interpretation as a personal name unlikely. It is more likely that the invocation is of ‘the og’, referring to some powerful being who could deal to anybody who desecrated a grave. (Yet note that there is some debate about the transcription and translation of hʿg, originally by Jean Starcky, ‘Une inscription Phénicienne de Byblos’, 1969.) Third, Byblos 13 parallels other tomb inscriptions (KAI 13.8 [the Tabnith inscription] and KAI 14.8  [the Eshmunazzar sarcophagus]) which also summon powerful beings to deal with desecrators of graves, except that the beings are the Rephaim (rpum). The Rephaim and the og are to some extent interchangeable on these Phoenician tomb inscriptions! Therefore, ‘the og’ might be interpreted as a powerful warrior and member of the Rephaim – all qualities which fit with the biblical King Og, except that the general noun ‘og’ has become a proper name, ‘Og’.

A weakness of Del Olmo Lete’s proposed tradition-historical development is that it provides a progression from myth to history to myth. More parsimonious and having the support of the factors listed above is a progression from a mythical early king and member of the Rephaim who is long dead but continues to exercise some power in the netherworld (including gravesites) to a ‘historicised’ or ‘euhemerised’ character believed to have the name ‘Og’ rather than the title of ‘og’, who is made a king in Ashteroth and Edrei and a member of the Rephaim.

The likelihood, therefore, is that Og’s name preceded his invention, in the Bible, as a person.

Updates:

1. Note the interesting comment in the comments section below by Chaim HaQoton: “the notion that Og was a title for the Bashanite King is already found in Medieval Rabbinic literature, see Daat Zeqanim [דעת זקנים] to Genesis 24:39”.

2. Jim Davila (Paleojudaica) comments on this proposal for the origin of Og, on his blog, that “something like that sounds plausible to me”.