'''Basic Trope''': A character is who often mentioned or referred to, but never appears.
* '''Straight''': AliceAndBob mention their childhood friend Charlie at almost every episode, but he is never seen onscreen.
** Alice and Bob mention Charlie all the time, mostly about a certain NoodleIncident, his outrageous personality and antics, and some NoodleImplements thrown in. Yet Charlie never shows up ''at all''.
** The main characters frequently mention several unseen friends of theirs.
** Alice and Bob just casually mention Charlie several times.
** Charlie is never seen, but [[TheVoice his voice is heard]] over the telephone.
** The closest we get to actually seeing Charlie are shots of his shadow and occasional glimpses of his hand.
** Charlie just never gets the chance to stop by; he could be holding multiple jobs, or busy with his other (also unseen) friends.
** Charlie is an anonymous witness.
** Charlie is on the run.
** If Charlie is only mentioned in the past tense, then he is possibly deceased.
** If the characters are children (or [[OneOfTheKids act like children]]), Charlie could be an ImaginaryFriend.
* '''Inverted''': Charlie is seen at almost every episode, but Alice and Bob never mentions anything about him. They had never even mentioned his name; it was said by a waiter at a café.
** Charlie finally appears at one occasion, and may or may not get a line.
** After three seasons of characters talking about Charlie, it is revealed that he is deceased. However, he is eventually seen as a ghost.
* '''Double Subverted''': Only for Alice and Bob to say that the person/ghost they saw was Charlie's brother. The real Charlie had important things to do.
** Charlie ''does'' appear but is either shown as a silhouette with a question mark, or covered by a CensorBox or a GagCensor.
** Charlie eventually appears ... [[NakedOnArrival naked]]. Because NakedPeopleAreFunny, of course.
** Charlie starts appearing, and [[RememberTheNewGuy everyone acts as if he's always been an onscreen character]].
* '''Zig Zagged''': ???
* '''Averted''': All characters ever mentioned appear at least once.
** The original plan was to have Charlie appear eventually, but the executives decide to make him an off-screen character.
** It's a biographical work about Alice and[=/=]or Bob. Charlie is Bob's best friend, so he has to at least be mentioned, but he could cause network troubles if directly confronted (he's a prostitute, gay, drug addict, etc.) so he is not shown.
** "You know how your loved ones [[TruthInTelevision talk about people you've never seen]]? Let's have our characters do that for the sake of realism."
* '''Lampshaded''': "You know, Charlie never seems to have time for us. I wonder what he's up to?"
* '''Invoked''': Charlie tries to visit Alice and Bob, but "Dylan the Villain" (actually an AntiHero) chases him off. All offscreen.
* '''Exploited''': Dylan wants Alice's friend Elaine to do an [[FridgeHorror unspecified]] dirty deed. Knowing that Elaine has never met Charlie, Dylan bribes her with a photo of him. [[TakeOurWordForIt (The audience never gets to see the photo.)]]
* '''Defied''': Someone finally manages to force Charlie onto the screen.
* '''Discussed''': "I've never seen Charlie. What's he like?"
* '''Conversed''': "There they go again, talking about Charlie. If he's so great, why don't we ever get to see him?"
* '''Implied''': The characters always refer to Charlie using pronouns (as in "I think ''he'' was the best friend I ever had,") in situations where no character who is shown would fit.
* '''Deconstructed[=/=]Reconstructed''': Not applicable. (This trope is completely realistic when played straight, as the characters would not necessarily notice the fact that the audience never gets to see a certain character.)
* '''Played For Laughs''': Any attempt to show Charlie onscreen by the characters ''will'' end up ill-fated: He never accepts invitations to anyone's house (maybe he's been called into work), any photos of him will be very blurry, and if he is supposed to appear on television, the set will break down (or the power will go out) just before he appears.
* '''Played For Drama''': Charlie is the only one with the answer to what is the cause of a series of unfortunate events that has been bothering the main cast.
You know, I don't think I've ever seen [[TheGhost the main page]].