Stanley and His Monster

Stanley and His Monster was a humorous fantasy series published by DC Comics back in the days when they didn't just do superheroes (the late 1960s, to be precise). Written by Arnold Drake with art by Winslow Mortimer, it concerned six-year-old Stanley Dover, who meets a large red shaggy monster that's more afraid of people than people are of it. Stanley adopts the monster as a pet, and names him Spot.

It was briefly revived in the 1990s by Phil Foglio, who wrote an issue of Secret Files and Origins (which revealed that Spot was actually a demon who had been booted out of Hell for being too nice) and a four-issue mini-series. The revival managed to make the fluffy whimsical series into part of The DCU without making it Darker and Edgier -- this despite the fact that the mini-series culminated in Stanley storming the gates of Hell to rescue Spot. An ongoing series did not result, and that's the last the world heard from Stanley and His Monster.

(Except for a guest appearance in 2001 in, of all things, a Green Arrow story arc written by Kevin Smith -- which was not fluffy or whimsical at all. Let's not talk about that. They also made a cameo in Infinite Crisis.)
 * A Boy and His X
 * Fluffy the Terrible: Spot
 * No Name Given: Spot's original name was never revealed. (The later Foglio version asserted that he didn't have one, unless "the Nameless One" counts as a name.)

The 1993 mini-series specifically provides examples of:
 * Adults Are Useless: Stanley's parents are at first bewildered, concerned, and freaked out by all the crazy things that happen... but by the final issue they've come to terms with it.
 * Captain Ersatz: DC wouldn't let Foglio use John Constantine, so he created an almost-identical character named Ambrose Bierce and hung a lampshade on it. And they wouldn't let him use Neil Gaiman's Sandman in a dream sequence, so Gardner Fox's original Sandman appears instead (but talks and acts as if he were Gaiman's King of Dreams).
 * Chekhov's Armoury: Justified -- When Stanley is preparing to go rescue Spot, Ambrose Bierce has him pick "Everything he thinks they will need", simultaneously casting a spell that creates a causality loop in which whatever Stanley picks will be exactly what's required. But it forms a kind of Plot Tailored to the Party as Stanley and the Monster will be unable to leave Hell until all the items are used.
 * Creator In-Joke: The references to the Heterodyne Boys in the first issue were this at the time, though they've become more famous since.
 * Darker and Edgier: Played with. Foglio seems to be seeing how many references to Vertigo Comics he can work in without the story ceasing to be light and fluffy. (Also, the cover of the first issue depicts Darker and Edgier versions of the characters, knee-deep in skulls -- being day-dreamed by an editor while Foglio pitches the light and fluffy mini-series to him.)
 * Historical Domain Character: Ambrose Bierce, John-Constantine-like occult detective, is supposedly the Ambrose Bierce, whose horror stories were based on fact. (His famous disappearance in the DC Universe was due to him going into hiding because an Eldritch Abomination was coming to complain about the write-up he'd given it.)
 * Occult Detective: Ambrose Bierce
 * Self-Inflicted Hell: Played with. The DCU's Hell is whatever you expect it to be, and Stanley is an innocent little kid whose knowledge of Hell comes entirely from Saturday morning cartoons and Spot's stringently self-censored stories -- so as soon as Stanley enters, Hell becomes cute, brightly-colored and harmless, with the demons forced to behave as if they were stupid and easily-outwitted. (Ambrose Bierce explains this trope; but not to Stanley, since it only works because Stanley doesn't know any better.)
 * Talking with Signs: Used by the angel Duma (The Voiceless) to communicate.
 * To Hell and Back
 * Treehouse of Fun: The first issue, before the main plot kicks in, revolves around Stanley's attempts to build the world's best ever treehouse, following the instructions in a book of Fun Things For Boys he finds in the attic, without his parents finding out.
 * Trenchcoat Brigade: Ambrose Bierce
 * The Voiceless: The angel Duma, which had been established as such in the pages of Sandman.
 * Whatevermancy: Ambrose Bierce gets involved after receiving a tip-off from a jellomancer, a person who can read the fluctuations of reality in jello.
 * Weird Trade Union: Ambrose Bierce is a card-carrying member of the Disreputable Urban Magicians and Sorcerers Union.
 * With This Herring: See Chekhov's Armoury above. Stanley storms Hell armed with a Halloween mask, a bottle of soda, an umbrella, a packet of hot dogs, a bottle of barbeque sauce and a little red wagon.

The Green Arrow crossover specifically provides examples of:
 * Captain Ersatz: Subverted; Morpheus himself makes a cameo.
 * Darker and Edgier: Really, this time.
 * Thank god it all ends on a (relatively) happy note;.
 * Harmful to Minors
 * One Steve Limit, subclass "If There's Two Steves, It's For A Reason": The Stanley-and-His-Monster part of the plot begins when Green Arrow meets an elderly man named Stanley Dover, who turns out to be young Stanley's eponymous grandfather.