Is there a term for the grammatical/rhetorical construction of "He-Who-Must-Not-Be-Named"?

Question

Is there a term for the construction of specifying someone or something solely via a relative clause without explicitly naming it, as in the example in the title - either at the level of grammar or of rhetoric? This seems like the kind of thing that there'd be an obscure Latin word for. It's kind of like an epithet, but not quite, because you only have the epithet and not the primary name itself.

Answer 1

I think it is a case of Antonomasia:

a literary term in which a descriptive phrase replaces a person’s name. Antonomasia can range from lighthearted nicknames to epic names.

The phrase antonomasia is derived from the Greek phrase antonomazein meaning “to name differently.”

Examples:

Rather than calling the dangerous man by name, all must call him “You-Know-Who” or “He-Who-Must-Not-Be-Named.” This usage of antonomasia emphasizes just how dangerous the man is, as most wizards and witches are too afraid to say his actual name aloud.

(literaryterms.net)

Answer 2

At the level of grammar rather than rhetoric, it seems that the construction that I described in the body of my question is called a "free relative clause".

The example that I gave in the title technically doesn't actually qualify, because of the presence of the pronoun "he", but semantically, it's a similar idea. (I think that in that example, the pronoun "he" is serving as a kind of "minimally semantic placeholder word" that's primarily there for a syntactic reason, and not to convey information about the person himself.)

Answer 3

That phase, I think, refers specifically to the Jewish religious convention of considering Jehovah's (Yahweh's) name as being too easily devalued by feeling free to speak it in regular conversation. There is a name for that. "Tetragram" or something like that. I understand that you are thinking of a more general term though.