Among the more colorful specimens of the human race you will find many who earned a sobriquet, or nickname — what we word geeks call an epithet. (Epithet, among other meanings, is also a euphemism for name-calling or other uncomplimentary utterances.)
From Alexander the Great to the King of Pop, memorable figures with such appellations have figured large in the public consciousness. But even these rulers have to submit to rules, so enclose any such epithet in quotation marks if it is enclosed in, or follows, the person’s actual name: “Charles ‘Lucky Lindy’ Lindbergh,” or “Lon Chaney, ‘the Man of a Thousand Faces.’” Otherwise no emphasis is needed.
Informal nicknames for people who don’t appear in history books follow the same rule: Whether he’s called Chip, Kip, or Skip, quotation marks are superfluous when you write about him.
Also capitalize but do not otherwise emphasize impermanent sobriquets such as “the First Lady” and collective epithets like “the Founding Fathers.” This rule is also pertinent for unnamed characters in films, plays, and the like: capitalize, but skip the quotation marks.
What about inanimate objects? Our solar system’s fourth planetary body long ago earned the nickname the Red Planet. Just as with personal names, omit quotation mark, but do capitalize; it’s a name, after all, not just a simple description that distinguishes it from the blue planet and the green planet and the yellow planet. The same goes for the references to terrestrial appellations like the Golden State (California’s sobriquet) or the Seven Wonders of the World.
And then there are conjectural places or entities like Memory Lane or Central Casting. Dictionaries and various style guides do not honor such terms with capitalization, but in my opinion, descriptions such as “Going back to my hometown, I took a trip down Memory Lane” and “The patrons bellied up to the bar were straight out of Central Casting” are strengthened by equating, with initial uppercase letters, the key words with real localities or institutions. (Defiant attitudes like mine are known in the editing trade as style breaks; consider this style broken here.)
Objects can also be generically personified. For example, traditionally, ships and other craft have been affectionately referred to by the female pronoun — not surprisingly, considering that those who perpetuated this affectation were men subjected to prolonged periods of duty aboard these vessels without the company of women.
This custom is acceptable in fiction, but employ the gender-neutral pronoun in all other uses.