It's strongly implied that Princess Bubblegum abandoned her son Lemongrab shortly after his birth because she couldn't handle the responsibility of raising a mentally unstable failed science experiment. According to Jesse Moynihan, a storyboard artist on the show, PB stuck him in a castle to be raised by servants. She acts like she's ashamed of his existence. This probably didn't do him much good.
In the flashbacks we see of Marceline's early childhood, her dad is nowhere to be seen. Made worse by the fact that she reallyneededaparent at the time. And she did find one in Simon Petrikov... but then he had to abandon her too, because his growing insanity was making him a danger to her.
At the end of season 5, Finn learns that his father is alive and is a prisoner in a crystal citadel. When we actually meet him at the beginning of season 6, he's less worried about making up for years away from his only son and more about escaping.
Then in season 8, he finally meets his mom. It is shown that his dad sent him to Ooo for his own safety.
Very few characters in All Hail King Julien appear to have parents, presumably as a result of predators. Of the parents mentioned, King Julien's parents left him to pursue a life of luxury (they were revealed to be alive in season 3, guest starring), and Maurice's parents abandoned him as a baby due to their traditions, and were killed by fossa sometime before the present day, Hector's mom was taken into human captivity when he was a baby, and Pancho is a Manchurian Agent unable to remember if he even had a family.
On Animaniacs, Skippy lives with his aunt with no mention of a mother or father. Years later, in an interview with The Nostalgia Critic, Slappy's VA Sherri Stoner claimed, in-character, that Skippy's parents dumped him on Slappy shortly after he was born, then left on a "sabbatical". Played straight however in Wakko's Wish where the Yakko, Wakko and Dot are portrayed as orphans, and it's implied that King Salazar murdered their parents when he seized power. It would actually make sense for him to have killed their parents as they were the real King and Queen.
Aang, like all Airbender children, was raised communally by monks, so it's hard to say if he even knew his parents. However his father-like mentor, his unknown parents and the rest of his nation were entirely wiped out while Aang was frozen in an iceberg. Hence the subtitle of the show. Katara and Sokka's mother was killed when they were young and as of the beginning of the show their father has left to fight in the war. They live with their grandmother who rather blithely sends them off to travel the world with Aang (though it is later revealed that she ran away from home herself, which perhaps explains her attitude). Toph deliberately runs away from her overprotective parents. This trope even applies to Appa.
The villains have it no better. Zuko and Azula's mother Princess Ursa is absent (to say the least) and their father, definitely not the overprotective type, seems to have no problem with sending the kid he actually likes halfway across the known world to hunt his enemies and/or drop the hammer on the Earth Kingdom. Zuko was banished on a Snipe Hunt (after being publicly disfigured and humiliated) for speaking out of turn when he was no older than fourteen. Mai's parents are seen briefly but seemingly have no interest or no say in her actions (possibly due to Azula's influence, though in "The Beach" Mai says that her mom repressed her a lot to not ruin Dad's high-profile political career) and Ty Lee's apparently did not notice when she ran away to join the circus, due to the 6 identical daughters.
Even the minor and one-shot characters suffer from this in spades — nearly every young person encountered by the main characters during their travels has lost at least one parent thanks to the ongoing war and its subsidiary disasters.
Played with for the main character who didn't live with her parents because once discovered as the Avatar, she was forced by her father and the Order of the White Lotus to be cooped up and safely trained, because of a plot to kidnap her. But she did get to see her alive and well parents every now and then up until the present. Nonetheless, she's the only main character lucky enough to still have parents.
Mako and Bolin lost their parents to a firebender in a mugging, and Asami lost her mother to a firebender during a raid... this didn't go over well with her father, who is now dead to her, and later in the literal sense .
Kuvira and Bataar Jr. from Books 3 and 4. Unlike most of the examples above, in which the parent died or left for the sake of their child, Kuvira's parents flat out didn't want her and kicked her out when she was 8, resulting in her finding her way into the Beifong household. Predictably, this pretty much shaped her actions as the final Big Bad, seeing her nation being abandoned just like she was. Bataar Jr. was also kicked out (or rather, kicked himself out) after aligning himself with Kuvira, but despite his betrayal he refuses to lose Opal to Kuvira's giant laser.
In Beavis And Butthead, their parents are sometimes mentioned but never seen, and they seem to take no real interest in the sometimes outrageous lives of their children. (In fact, the only who's ever mentioned with any regularity is Beavis' mother, who is said to be a slut; we find out in the film Beavis and Butt-Head Do America that the boys are the bastard sons of two heavy-metal roadies, and possibly half-brothers (Mike Judge refers to the two as their "dads", however). It could also be the dads are brothers, or half-brothers, making the guys cousins.
Xylene from Ben 10 explains her species, Uxorites, leave their children to fend for themselves as soon as they hatch, and as such cannot understand the concept of parenting in other species.
In Birdman, in the debut episode of Birdboy, Birdman's on-and-off sidekick, the lad is found separated from his father after an encounter with a supervillain. Birdman promises to help him find his father, but nothing ever comes of it. (His mother is never mentioned.)
Boo Boom! The Long Way Home: the main character, Boo-Boom, is separated from his parents in the first episode due to an air attack on the truck that was transporting them. They don't get reunited until the end of the series.
The Boondocks: Huey and Riley's parents are never seen or mentioned, and it is not known how they came to live with Granddad. It's pretty heavily implied that they're dead. Partially a case of All There in the Manual, or at least in the comics. Their parents are dead, and in the first episode Granddad mentions spending their inheritance on that house (explaining in part why they were able to move to suburbia, hence, the boondocks).
Captain Planet and the Planeteers: Free room and board on Hope Island is part of the Benefits Package of being a Planeteer, so even the few parents who are still alive are mostly out of the picture.
Gadget from Chip 'n Dale Rescue Rangers lost her father a year before the team was formed. Due to lack of information, many fan theories exist about what actually happened. Her mother is never mentioned. This may be explained at some point in the current comics.
Chowder: The whereabouts of Chowder's parents (and of Panini's and Gorgonzola's parents) are never revealed or discussed.
Daria Morgendorffer's home life is made more interesting due to her needy self-obsessed father - a man who lives in his own unhappy childhood and still has issues to resolve - and her workaholic mother who places job before family for the greater part of the time. This is one of the factors that shaped the Princess of Snark's alienation and mordant cynicism.
That is nothing compared to the home life of Jane Lane. There is a reason why Hands-Off Parenting was formerly called Casa Lane Parenting because the Lane parents just ... weren't there and left their kids to their own devices.
The Davincibles: Pablo and Zoë Davinci live with their uncle Leo, who is apparently also their legal guardian. No mention is ever made of their parents.
Parents in Dragon Booster are suspiciously absent, considering that their offspring are competing in dangerous sports with giant reptiles. Parm has a mother, mentioned once and never again, and Kitt has apparently left home or is an orphan (nothing is ever said about her parents). Only Artha (the protagonist) and Moordryd (his rival) have onscreen parents: Moordryd's dad is the Big Bad, while his mother, Zulay, is implied to be dead (the ambiguity of the line spawned numerous fanfics), while Artha has quite possibly the worst case of Parental Abandonment ever: his mother is never mentioned, while his dad, Connor, disappears in the first episode and is presumably dead... right up until the second season finale, when it is revealed that Mortis, who's been helping the heroes the whole time, is Connor in disguise. The reason for abandoning his children and letting them believe he was dead? They wouldn't have become independent.
In Ed, Edd n Eddy, we never see anyone at all in the show except for the children that live in the neighborhood. Sometimes parents and older siblings are alluded to, but they are never actually shown.
Tom, along with Princess Katherine, The Magus, Tom's mother, Mary, & Finella, fled from the castle of King Kenneth II when he was slain by Constantine, who later usurped his throne. After using the Grimorum to find a way into Avalon, The Magus is forced to give up the magical book because it can't be taken into Avalon. To keep it away from Constantine, so he won't be able to find them, Finella volunteers to protect the book and go into hiding from the King of Scotland. Mary volunteers to go with, deciding that protecting this magic book is more important than raising her only child, who at this point in the story wasn't even ten years old.
Demona didn't even try to stop the Magus and Katharine from "stealing" the eggs from the Wyvern Rookery, even though one of those eggs held her own child. In an unusual twist, the Magus and Katharine had in fact been entrusted with those eggs by Goliath, and they ultimately took better care of the eggs than Demona herself could have done, making this a rare positive example of this trope.
Soos' dad left him when he was very young and never visited, only sending postcards. His grandmother reassures him that he'll visit someday, but in some (Spanish) lines she says to herself, it's clear she thinks the father is a terrible person. As for his mother, we never see her.
And of course, Dipper and Mabel's parents are only seen briefly in the first episode (even then, only their arms are shown) where they send them to stay with their grunkle Stan for the summer just to get them out of the house.
Neither Fee nor Foo from Harvey Beaks apparently have guardians. They're feral kids who live by themselves and no one bats an eye.
in the original, Teela knows she's adopted, but not her parents' identity; Duncan claims her father was a "great warrior" (the only time he is mentioned), and that her mother's identity is a secret he's sworn to keep, promising her she'll learn it someday, but not from him. She does, and her mother tells her that she is also her heir, but can only retain the knowledge when ready to claim that birthright. (He-Man learns the secret and remains a confidant, but the issue is not addressed again.)
In the remake, Teela is also her heir, but believes Duncan is her true father and that her mother is dead. Duncan is not as accepting of this, scolding the Sorceress for failing to be a proper mother. Unfortunately, the revelation of the power within her only proves the Sorceress has a valid point, as she mishandles it. A later episode shows flashbacks of the past, including Teela's father, a wounded amnesiac soldier. It is hinted that Duncan may well be her biological father, but it is also hinted later that it may be Duncan's brother, Fisto. In any case, the series ended before this could be explored more.
Inspector Gadget's niece Penny. He seems to be her only relative, although the backstory is pretty non-existent for her.
Dib and Gaz of Invader Zim have a father that is more concerned with his latest invention and his television show than whatever his children are doing, and a mother who is never mentioned (naturally, Epileptic Trees abound). Zim himself is a borderline example, as while technically he has no parents (Irkens are grown, not bred), his entire motivation is pleasing the parental figures of the entire species, the Tallest, who hate him and exile him to the far end of the known universe.
Jade is left by her parents in the first episode, and although they are alive, they are only referred to twice during the rest of the series. Jackie as well, it is implied, was sent to America to train with Uncle when he was a kid. His parents are never mentioned.
Paco's parents are never mentioned and it's possible they don't exist at all. El Toro, who is probably not his father, serves as a father-like figure to the boy.
It's honestly easier to find Jem characters with parents in their lives than ones who don't. So many have missing parents.
Jerrica's and Kimber's father died of a terminal illness at the start of the series; the first scene is his funeral. Their mother died when they were children in an airplane accident, and Jerrica especially holds baggage about this because she got into an argument with her mom before she left.
Aja and Shana only refer to their biological parents once in a single passing line in "Father's Day" where they apparently have video tapes of their biological fathers. They were the Benton's foster children.
Jerrica's mother was a foster child herself and that's why she wanted to foster children.
Pizzazz's mother abandoned her and her father at a young age. Her father was distant to her growing up and spoiled her with gifts instead of actual affection. This is a big reason why she ended up so rotten and an Attention Whore. Partway through the series, Pizzaz's father gets fed up with her and essentially disowns her.
Roxy never mentions her parents but we know she ran away as a teen. Stormer's parents are never mentioned either. Jetta is the only Misfit with two, known, living parents. Their groupie, Clash, has two parents too and in fact is a Daddy's Girl. Pizzazz is utterly perplexed that a father could adore her child.
The main characters run a foster home called Starlight House. None of the girls reference their parents except for Ba Nee, who is bent on finding her presumably deceased father and we know her mother has passed. All she knows is her father was a redheaded American soldier. In the final episode she is reunited with her father, who had amnesia about his events in the army and didn't even remember marrying her mother until his memory cleared up.
Reoccuring character, Danse's parents are unknown for most of the series. There's an episode all about her parents though. Her mom was a famous ballerina who fled Yugoslavia for America but her whereabouts are unknown. Her father was presumed dead but is alive.
Minx's and Rapture's parents aren't mentioned but their bandmates Riot's are shown. His father is a masculine former army member who disapproved of his son being into music, which he deemed for women and 'sissies'. He disowned Riot when he quit the army to be in a band. Eventually they reconcile after Riot's mom ends up hospitalized due to stress related to her husband and son fighting.
Kaeloo: One of Mr. Cat's Multiple-Choice Past backstories had a particulary cruel example where shortly after he was born, he was tied up in a sack and thrown into a river to drown. Fortunately, he was saved by a salmon and raised by it.
Charlotte from Making Fiends claims that her parents are astronauts in space, however, the series implies that her parents are dead.
In Max and Ruby, Ruby and Max's parents are never mentioned. They do have a grandmother. Possibly the only character with a parent that's seen in-show is baby Huffington, whose dad runs a shop in town.
In Moral Orel, Joe's mother Nurse Bendy left him with his father, although he thought she died, as his father told him.
Adam Lyon of My Gym Partner's a Monkey seems to have parents, but they don't seem to object to him attending middle school with the animal kingdom. They explained why in one episode but we couldn't understand them (they have fur allergies and were in containment suits at the time).
Applejack, Big Macintosh, and Apple Bloom's parents are never seen, with their family matriarch, Granny Smith, acting as their guardian. While Applejack and Big Macintosh are at least old enough to live on their own (they stay on their farm due to the family business), Apple Bloom clearly isn't. Made even stranger seeing as the Apple family is the most detailed in the show. Word ofFaust and says that she and and her crew tried to come up with an explanation for where their parents were, with ideas such as them being travelling salesponies or simply being dead, but they never figured out what to do with them, so it's left ambiguous in the series.
Many fans thought the Season 3 episode "Apple Family Reunion", with a title like that, would finally shed light on the situation. It doesn't. There's a whole Continuity Cavalcade of every single Apple member seen in the series up to that point and even several new members, but if Applejack's parents were there they weren't identified. The closest we get is a pair of shooting stars that show up twice, which a storyboard artist has said is symbolic of their absence, which could mean a great many things.
This was ultimately addressed in the Season 7 episode "The Perfect Pear," which showed the Apple siblings' parents and how they ended up together despite their hardships, along with very strong hints that both of them are dead. They're spoken of exclusively in the past tense, several characters tear up when reminiscing about them, and Apple Bloom speaks of things to "remember them by."
No word on who Spike's biological parents are. All that's known is that his egg was in the care of Princess Celestia and was hatched by Twilight long before the series began.
Scootaloo has no known biological relatives to speak of either. The closest we get is "Parental Glideance" implying she doesn't have supportive parents, whatever that means.
Implied in Ni Hao, Kai-Lan; Kai-lan's parents are never mentioned or addressed, even when other family members are featured.
In The Oblongs episode "Milo, Interrupted", it is revealed that Helga's parents left on vacation a year earlier and never came back... until the end of the episode, where it is revealed that they survived by eating the other passengers on the plane they took after it crashed.
Some fans have noted that throughout the whole first two seasons, Vanessa seems to be the only child/teen character with two biological parents; everyone else seems to have a mom but no dad (or in Django's case, a dad but no mom). This recently changed when we finally saw Jeremy's father.
Doofenshmirz's parents couldn't even be bothered turning up for his birth.
The Scooby-Doo gang members either have no parents or just very hands-off parents who don't seem to care that their teenagers go all around the world, hunting down villains in Halloween costumes. Subverted in the 'Scooby-Doo! Mystery Incorporated'' series.
In The Smurfs, King Gerard's parents are notably absent from his life at the time he first appears as Prince Gerard in "The Clockwork Smurf". His aunt Imperia has taken care of Gerard, but desires to be coronated queen in her nephew's place, so she has him confined to the dungeon up until his twelfth birthday, where he will be Released to Elsewhere...a plan that was foiled by the arrival of Clockwork Smurf.
Steven Universe: Jasper's criticism of Amethyst being overcooked indicates her abandonment at the kindergarten was intentional. Though this DEFINENTLY wasn't the first time Amethyst had to experience this, as Rose hung out with her less when Greg came into her life, and Pearl and Garnet began to treat her as worthless when Rose left.
Steven himself subverts this, as while his father Greg doesn't live with him (due to the Gems), Greg does spend as much time as he can with him, and not only pays for Steven's expenses, but also built the house he lives in by hand. However, Greg's former manager Marty plays this straight with his son Sour Cream, having apparently abandoned Sour Cream and Vidalia after he was born, rarely seeing him (the last time before "Drop Beat Dad" being nine years before).
The entire main cast is made up of 14-year-olds, and the show is one of the awkward cases in which nobody even mentions their parents. The closest we ever get is an aunt. And considering how many times they brush death, it's amazing they're allowed out of the house at all. (In fact, the only brothers we see freely admit to hatching out of eggs, leading to much speculation about how exactly the cast are born.)
In "Origins", Aerrow mentions that his, Finn's, and Piper's families and home terras were destroyed by Cyclonians. Stork mentioned an attack on his own terra, but nothing about his parents; Junko is similarly vague.
It is also heavily implied that Lightning Strike, the last leader of the original Storm Hawks, was Aerrow's father. Sure, Aerrow's only ever referred to as a "descendant", but considering Lightning Strike died in his twenties or thirties 10 years before the start of the series and Aerrow is 14...
In the cartoon Super Robot Monkey Team Hyperforce Go!, Chiro's parents have never even really been mentioned. If he had different caregivers than his parents, they aren't mentioned either. The kid just walks into a Super Robot, befriends some robot monkeys, and no parent/guardian seems to even care where he is. (Aside from the fan theory that Skeleton King may be Chiro's father.)
Lance from Sym-Bionic Titan. His father supposedly died when he was very young, and he presumably had a Missing Mom, because custody was more or less given to the king and Modula, who sent him off to a military boarding school.
The Titans are conspicuously independent, lacking even mentorsuperheroes (* cough* Batman * cough* ). However, many of their parents are actually accounted for: Robin's origin, although it is never covered in any detail, is hinted at in one episode and would dictate that his parents are dead. It also comes up a couple times in season four: Raven's mother appears briefly in one episode, and her father is a demonic overlord named Trigon (also evidently dead by the end of the season). It is also implied that Cyborg's parents and Beast Boy's parents have passed on, as well.
There's no excuse for Starfire though. In one episode they go back to her home planet, and are greeted by her "nanny". The rest of the episode involves Starfire's evil sister Blackfire usurping the throne and trying to marry Starfire off to stop a war. The fate of the original king and queen? Never mentioned.
The comic book, Teen Titans Go!, explained that they fell ill after their son (and Star and Black's brother), Wildfire, was sent off the planet and never recovered from it.
The Venture Bros. uses a weird version of this in "Powerless in the Face of Death". You might call it a backwards subversion. It opens with a montage of Dr. Venture's month-long trip around the world to "find himself". Brock is chasing after, to get him to come home, face his responsibilities, and "deal with what happened to the boys". Doc's sons had been killed at the end of the previous episode, so this seems to mean that he is just running from his grief, and Brock wants him to come to terms with it emotionally. What gradually becomes clear is that "dealing with it" really means replacing the boys with a pair of reprogrammed clones, which Doc has done fourteen times before. (The boys are rather death-prone.) So his procrastinating a month on this does amount to Parental Abandonment, although his sons never knew it.
Voltron: Legendary Defender: Keith was orphaned at a young age; it's confirmed that his mother left him, and in a tie-in vlog video on Dreamworks' Youtube channel, he theorizes that this might be the part of the reason he seems to push people away before they can reject him. While it's left to be confirmed whether his father died, or left as well, he does describe Shiro as "the only one who never gave up on him", so the latter seems like a likely possibility. Needless to say, Keith's abandonment issues run pretty deep.
X-Men: Evolution is worthy of mention for its almost complete aversion of this trope. Despite living away from home, all the teens except Scott and Rogue have a loving family or foster-family to go home to in the obligatory Christmas episode. Kurt suffers from combined Missing Mom / Parental Betrayal, but still notes that his foster parents are great to him. The Brotherhood, on the other hand, have not fared as well — their parents are all absent for no apparent reason, Jerkasses, or the Big Bad (Quicksilver does seem to be treated pretty well, though, all things considered).
The titular bunnies from Yin Yang Yo! have Master Yo the panda as their sensei and father figure, but so far their parents have not been mentioned... though some of their friends (and enemies) have parents ("CAAAAAAARL!"). It was later revealed that Master Yo IS Yin and Yang's Father.