The Amory Wars: Coheed and Cambria are forced to kill three of their four children early on, with the youngest (the twins, Matthew and Maria) getting poisoned and the oldest (Josephine, who had gotten engaged, and shortly after, gang raped while her fiancÚ is beaten) getting beaten to death with a hammer. The second oldest, Claudio, was out with his girlfriend when it happened, and when he gets home he finds Josie dead on the kitchen floor.
52: The Question is suffering from terminal lung cancer exacerbated by years of smoking as his body and mind gradually waste away. Despite his history of fighting alien menaces and international conspiracies there is nothing he can do to stop his cancer from metastasizing.
The kids from Runaways fight vampires, aliens, and evil robots, but the only reason they have to deal with these things in the first place is that their own parents turn out to be evil. For most of them, this comes as a shock; for Chase, not so much. Then they all start living in underground hideaways and putting themselves in danger to keep LA safe from the power vacuum created by their parents, resulting in even more physical and emotional trauma and, in Gertrude aka Gert's case, death.
In one of the earlier chapters, Frank Dean attacks other members of the Pride and completely freaks out when Karolina disappears.
When the kids accidentally travel to the past and run into the Yorks (before they died), the Yorks are quite panicked and ask straight away if their daughter is with them. When they learn that Gertrude is dead, they immediately plan to return to her and make sure she's safe. Then they bring over a futuristic bomb to get revenge on the kids for letting Gert die in any timeline.
In the Age of Ultron alternate universe Victor Mancha is the caretaker of a bunch of orphans, and the last of the original Runaways alive. The Ao U Mancha has two simple fears, less glamorous but scarier than his past ones: he fears to be unable to protect his protegees, and he fears the day he'll start forgetting about the past and the happy moments he shared with his now absent friends.
Hey, remember those "terrorist organizations" that used to show up in Saturdaymorningcartoons? Wearing identical uniforms and commanded by hamfisted martinettes with delusions of grandeur? Well, then take a look at the JSA vs Kobra minseries, in which a chess-playing former analyst takes control of one such organization, and proceeds to turn it into, well, a terrorist organization - members who could be anyone, improvised explosive devices - but with all the reach and potential resources of a Fantasy Kitchen Sink universe. Ever wondered what a terrorist organization would do mind control magic and bargain basement enhancile tech?
The Marvel Comics event Fear Itself is ultimately driven by Odin's fear of losing his son Thor and the desperate, insane measures he takes to prevent it from coming to pass. He fails.
Scott Lang entire tenure as Ant-Man. He became a petty thief due to his inability to support his own daughter, and faced jail time for that. Freed, he was forced again to steal, this time the Ant-Man duds and Pym Particles because it was the only way to get a doctor able to cure his daughter's failing heart. Ultimately, dad and daughter were able to enjoy a few years of happiness: just for Scott Lang to see Cassie brutally killed in front of his eyes. Ouch.
My Little Pony: Friendship Is Magic (IDW) kicks off with the Cutie Mark Crusaders up to their usual adorable shenanigans, trying to get their cutie marks in Fluttershy's backyard... and then they get attacked by animals.
In issue five, the main cast is plagued with nightmares that are disturbingly mundane and realistic: Twilight dreams about being rejected by her mentor, Applejack dreams about not being able to provide for her family, Rainbow Dash dreams about her wings being broken, etc. All of them are things that more terrifying due to the fact that they could actually happen.
In the very first issue of Godzilla: Kingdom of Monsters, a pair of kids are killed when Godzilla makes his arrival. And it doesn't stop there. Another kid gets swallowed alive by Rodan, a girl loses her parents and brother to Godzilla and she gets a concussion during a fight between [MechaGodzilla] and Anguirus. The sequel series has the main character Boxer lose two girls, one being a girl he was a bodyguard for and the other was his daughter who was killed during Godzilla's landfall in Los Angeles.
Gangsters and Goliaths, what sets Makoto Sato off on Takahashi is the latter threatening his sons.
Godzilla Legends has a young psychic boy getting kidnapped by shapeshifting aliens who want to use him for his psychic connection with Titanosaurus to aide in their conquest of Earth.
In Clara...de noche (aka Betty by night or Betty by the hour) Adult Fear is one of the drives behind Betty's decision to keep being an hooker. She began whoring herself some years before the birth of her son to support her deadbeat father at first, then herself. Then, her son happened, and she keeps selling herself to grant him the lifestyle they grew accustomed to, knowing that, in time, she'll lose her livelihood along with her beauty. She also tried more menial jobs: her livelihood was so severely reduced that she was quickly forced to return to her main and more lucrative profession.
Played for Laughs, due to the comedical nature of the series, but really much the primal Adult Fear: Betty is really competent at her job. But she loathes it, and, furthermore even her son, when he's not appreciating their nice home, his fancy new toys and having the happy childhood her mother lacked, seems ashamed to have a Single Mom Stripper as a single parent. However, she can't leave her work without having her son potentially fall into the same hardships and misery that brought her on the streets beforehand, but, also, she's painfully aware that her biological clock is ticking, and someday she'll be just too old to keep on with their lifestyle.
Batman villain Scarecrow's main schtick of using fear gas usually produces horrifying but improbable hallucintions, like being covered in spiders or suffering some kind of Body Horror, but some of his victims cry out in fear for loved ones or memories of past abuse. Batman, for one, is forced to relive the murder of his sidekick and adopted son, Jason Todd when exposed to fear toxin.
Your ex shows up, demanding the return of the child you two share, who she'd previously placed large bounty on, and threatens to destroy your whole city if she doesn't get her way. You try to fight it, but your allies keep falling, and in the end you have watch as your son is murdered by one of your ex's minions. Yeah, there's a reason Batman is progressively losing it in the Batman and Robin title.
Some of the concepts in X-Men plays pretty heavily on this. Some people view mutants as monsters, meaning your child might turn out to be this. Even for those who accept mutants, God Loves, Man Kills give us the image of two small children murdered on a playground simply because they are mutants: the world is full of danger that preys on the vulnerable.
Perhaps no more potent for any character than for Chris Summers. Bad enough that he thought his sons were dead. Turns out they survived, but the mistreatment in their childhoods left quite a lot of damage. He is still trying to protect Scott, to keep from losing him... again.