Invisible Parents

Unlike in some series where a young hero either lacks a mother or father, or has parents so incompetent that they might as well not exist, this trope pertains to a character that does have parents, but they are just never seen. It doesn't have to be the case that the child is neglected. Their parents are probably as good as any. It's just that the audience never or very rarely sees them due to their lack of importance to the plot.

Anime and Manga

We never see any of the girls' parents in K-On!, except during an imaginary sequence of Yui and Ui's parents happily spending Christmas together in a foreign country.
- We eventually see Yui and Ui's parents for real in The Movie, right before Yui leaves with the other senior girls on a trip to England.
Despite it mimicking K-On! in many other ways, Bakuon!! actively averts this trope for most of its cast -- for example the girls meet Onsa's father, and we see both Rin's father and Chisame's parents at home and in flashbacks. However, the parents of Hane and Yume (the Yui and Ui counterparts) are explicitly said to be in America long-term, and never appear in the series. And Raimu/Line, unknown to the rest of the cast, is actually an adult in her thirties (at least) charged with keeping an eye on the girls.
This is extremely common in dating sims, visual novels, and the anime based on them. Characters are typically adolescent and live with their parents but despite the fact that they all know each other and go over to each others houses frequently, even date each other, parents always seem to be conveniently absent if not dead and play no role in the story. Number of parents is usually limited to a single attractive mother or something similar.
Several characters' parents from Naruto. Sakura's are probably the most notably absent (despite being almost stated to be there) but there is also Lee's parents (if he even has any!) and Neji, Hinata, Choji, Ino, and Shino's mothers (though we see Hinata and Chouji's in the anime; the former in a flashback).
The dub of Yu-Gi-Oh removes Yugi's mother from the show entirely. She doesn't appear that often in the original show, though, and there is no mention of Yugi's father.
Pokémon Ash leaves home at 10 and after a few episodes his mom is shown less than just about any Pokemon from the current generation.
- The protagonists' parents in Pokémon Special rarely have visible parents either, except in the Ruby&Sapphire arc.
Sailor Mercury's mother in Sailor Moon. It got to the point where she has to go to the airport to leave for America and her mother isn't there with her and nobody even comments on it.
Pretty much all the Sailor Senshi have this problem, except for Usagi. In the manga, Sailor Mercury is one of the very few aversions to the trope, where both her mother and father are shown sympathetically despite being divorced.
The entire cast of School Days.
Almost all of the parents in Princess Tutu, probably because the bulk of the story takes place in a Boarding School.
Sasagawa Ryohei and Kyoko from Katekyo Hitman Reborn. The manga has never even hinted at them having parents.
In Hayate the Combat Butler, on a trip to a hot springs, Hinagiku's parents are supposedly taking her on the trip as a late birthday present since her father couldn't be there for her birthday. Neither parent is ever shown through the entire arc, even after Hinagiku faints in the hot springs and needs to be fished out.
- Most of the characters parents are mentioned as either: dead or run away (leaving the children with massive debts).
Alisa and Suzuka's parents in Magical Girl Lyrical Nanoha are never shown. The closest we get to meeting them was the cast-wide picnic they were invited to in the third Sound Stage of A's, where they remained unheard and obviously unseen, although Alisa is once heard speaking to her father. Same goes with the parents of Rio and Corona of ViVid, who we only know exist via side-comment from Fate-mama. Then again, both pairs are Those Two Guys.
Sola. Nobody's parents are ever seen, heard, mentioned, or even alluded to. Can result in Fridge Logic when the entire incident of Takeshi breaking into the protagonist's house to kill his girl- among others -goes completely unnoticed.
In Love Hina the parents of many of the residents of Hinata House seem to be completely absent. Keitaro's parents are never seen in either the manga or anime. Naru's and Shinobu's parents are seen in the anime, but not the manga. Kitsune, Motoko, and Suu's parents are also nowhere to be found.
In SEX teenagers Kaho and Natsu get involved with delinquents, the yakuza, and criminal activities, plus the US army; Kaho goes to live with two guys and gets involved with an assassin, Natsu bombs people, gets shot and kidnapped... without even a mention of a reaction from their parents. (Natsu's dad is mentioned once early in the story, as a plot device, and that's all.)
In Bakuman｡, Moritaka Mashiro talks with his father once on the phone, but he is never seen in person, and it's been noted that they don't talk often. Miho's father has also not appeared in the series yet.
Parents are never seen, and barely even mentioned in The Melancholy of Haruhi Suzumiya. The only times this was averted are Kyon's little sister briefly saying something to her mother, and when Haruhi told Ksyon how her father took her to a baseball game as a child, and for the first time she understood how many people there are in the world. Even in that flashback only Haruhi herself is actually seen.
In Detective Conan Ayumi, Mitsuhiko, and Genta's parents are almost non-existant, as these kids can go off to a dangerous mystery case on a whim, as long Professor Agasa is at least supervising. There was an earlier episode where the parents are seen for a few seconds, then they don't really make an appearance ever again. Ayumi's mom's voice spoke once when leaving her apartment, and Genta's dad was a suspect on a episode.
In Zegapain, the absence of parents is explained, Everything is a computer program. Mopst of the "actual people" are teenagers or adults. Parents would just take up more data space. "Does not seeing your mother really have much effect on your everyday life?" is actually said by one of the characters who is pointing out that the hero has never seen his mother though he hears her voice as she leaves for work and she leaves food for him in the mornings.
In the Little Witch Academia franchise as a whole, most students studying at the Luna Nova Wizarding School don't have on screen parents, or any family for that matter. Occasionally, some parents will appear in the series, like how The Ace Diana Cavendish's family plays a role in the "Cavendish" episode (even then, it's her family that advances the story, not her parents). The Nice Girl Lotte's parents appear in an episode, when the red trio are visiting them. Parents of characters like the Fiery Redhead Amanda O'Neill, The Hero Atsuko Kagari, and the mushroom-obsessed Sucy are never shown.

Fan Works

Yu-Gi-Oh!: The Abridged Series lampshaded this when Tristan asked Tea, "Don't our parents even care that we're missing?"

Literature

Hermione's parents in Harry Potter. Because they are Muggles, they are not very connected with the happenings of the magical world.
- Her parents do appear once in the books, taking Hermione to pick up her things in Diagon Alley. They do not interact with the rest of the cast in any substantial matter. Beyond that, they are merely referenced without appearing.
  - They are, however, shown near the beginning of the movie Harry Potter and the Deathly Hallows: Part 1.

Live-Action TV

Pretty much all the Scoobies' parents except Buffy's mom on Buffy the Vampire Slayer.
Salute Your Shorts
Saved by the Bell
Many of the parents on Glee, but especially Rachel's gay dads. Other less prominent characters have had their parents appear as the plot needed, but her fathers have never been shown on screen, save for a photo. Perhaps they're still on that cruise.
On Gilmore Girls, Lane's mother is a fairly prominent character, but her father is never seen. Less observant viewers might think her father is dead or her parents are divorced, but there are several instances where Lane mentions her parents and implies she lives with both of them.

Newspaper Comics

The entire cast of Peanuts, but more as a result of the franchise's insistence on leaving adults off-screen (save for several early installments and a couple of the movies) rather than because they are literally missing. We know that Charlie Brown's father is a barber, has given advice to him and cuts his son's hair. And Linus, Lucy and Rerun's mother is literally just barely off-screen in all the strips where Rerun rides in a child seat on her bicycle.
Susie's parents are never seen in Calvin and Hobbes despite Calvin visiting her house several times. Susie and Calvin even speak to Susie's mother on two separate occasions, but she remains off-screen both times.

Video Games

Ness' dad in EarthBound. Aside from the occasional phone conversation he might as well not exist. He is probably a Salaryman.
Likewise, Mom in Animal Crossing series, who exists only as a source of letters.
Everyone's parents in Persona 3 and (except for Kanji's mom and the Dojimas) Persona 4.
- Well, except for Yukari and Mitsuru's fathers, who are rather important to the plot, Akihiko, Ken, Shinji, and the Main Character's parents, who are dead, Junpei's father and Mitsuru's mother, who are also dead, Aigis, who doesn't have parents, and Koromaru's who are irrelevant. That leaves all of both of Fuuka's parents and the mothers of Yukari and Junpei.
In Kingdom Hearts, we hear Sora's mother early in the first game, but never even see the parents of anyone on Destiny Islands.
Super Mario Bros.: For the most part, Mario and Luigi's parents. They are mentioned, but almost never seen. Then again, in most of the games they both seem to be in their thirties or forties, a time of one's life when one doesn't necessarily have daily contact with one's parents.
Hisao's father in Katawa Shoujo only appears in one scene in the prologue, and does not have a sprite, like many of the visual novel's extremely minor and nameless characters do. Lilly's mother is heard on the other end of the phone in Hanako and Lilly's routes.

Web Original

All five of the flagship series of Platypus Comix feature characters whose parents are either never around or rarely appear. Sometimes it's justified, in comics where the main characters are young adults.
Although there are mentions about Eleonora and Menelaos having a home and a family in Greek Ninja, they are never shown, neither are any of the other characters' parents, characters who are students in Ariadnio and assumed to have parents.

Western Animation

The various Peanuts specials involving Charlie Brown and other children.
Same thing for Ed, Edd 'n' Eddy.
Most of the parents in Code Lyoko, again since the action is within a Boarding School. The exception is the Ishiyama family, who have a bit more screen time since Yumi isn't a boarder. Ulrich's, Odd's and William's parents do appear over time, as well as Jérémie's father. By the end, Jérémie's mother has only been mentioned in conversations with his father and Sissi's mother is completely unaccounted for.
In Beavis and Butthead the two main characters are established to live with their single mothers who are implied to be prostitutes. The duo occasionally mention them and sometimes call to them but we see them only once.^[1] However we do meet their dads in the movie: Motley Crue roadies just as stupid as their sons and their behavior is similar to theirs, that don't seem to notice their resemblance to them and abandon them after providing them with a fire for the night.
- Based on the foursome's conversation, Beavis and Butthead are half-brothers and one of the roadies is their Dad.
Parents are only very rarely seen in Recess

↑ and both mothers resemble the other's progeny

[1] th mothers resemble the other's progeny

[1]