Grammer ignorami. Proper nouns should NEVER be preceded by articles.
Oh, the definite article is very commonly used before proper nouns, most often place names or geographical features (e.g. "The Mississippi (River)").
Sometimes "the" is used purely customarily (particularly in names translated from other languages like "The Ukraine" or "The Maghreb" ), but its primary function is to distinguish between nouns referring to specific things a speaker is expected to be aware of, and generic things that are just being introduced into the discourse: "a ball [which I haven't mentioned up until now] broke Mr. Smith's window; Mr. Smith kept the ball [which I just mentioned]."
In particular proper nouns which sound like they might be generic will sometimes customarily get a "the" tacked on to indicate the audience is expected to picture the well-known thing rather than some unknown one ("The United States", "The Great Lakes", "The Big Easy"). "The Donald" is a definite article usage of this type, with an bit of ironic deprecation mixed in.
By the way the plural of "ignoramus" is "ignoramuses", not "ignorami". That is because "ignoramus" was never a noun in Latin; rather it is a conjugation of the verb ignorare (to be unacquainted with, to ignore). "Ignoramus" entered English as a legal term to mean "we take no notice of" (e.g. a witness whose testimony is irrelevant because he has no firsthand knowledge).