Aquaman: In Aquaman (New 52), Orm is noticeably less evil than beforeFlashpoint, but he regards land-dwellers with disdain. When the prison he's kept in is destroyed, he leaves, but not before murdering one of the guards who was nice to him as thanks (which he does seem to regard as a mercy considering the man was wounded and likely was going to die a more painful death at the hands of the prisoners). He meets a woman, Erin, on the way to the sea, whose son is being attacked by escaped prisoners. He disregards her and tells her that when he was Tommy's age, 8, he had learned to defend himself, and it's her fault for not teaching him. He leaves and goes back under the sea, before returning to help them while admitting that 8 is too young an age to die. Later, it is revealed that he stayed with them through the Crime Syndicate's invasion of Earth.
Believe it or not, even a Chaotic EvilCard-Carrying Villain like the Joker does these every now and then. One issue of Deathstroke had him rescuing a small girl from her abusive Sleazy Politician father (setting her up to go live with her mom instead) at absolutely no apparent gain to himself (well, okay, he "rescued" her by poisoning the city's blood banks and using that to coerce the politician, but if that was all he wanted he could've just gone ahead and done it; after the girl's safe, he even leaves the antidote behind!).
When Gotham City is destroyed by an earthquake in Batman: No Man's Land, Poison Ivy takes over the city park and makes it a haven for the city's orphaned children, caring for them like her own children. When the police see her as a dangerous terrorist and try to take back control, the herbicidal chemicals they use poisons one of the girls inside, and Poison Ivy chooses to give herself up to save her life.
In another story, Ivy uses her mind control abilities to make sure Jerkass negligent father pays for his son's art school tuition.
Bone: Kingdok prepares and brings food to the two stupid rat creatures for inadvertently doing him a favor. Unlike most examples, Kingdok actually retains most of his scariness and menace as he's doing this.
The Cartoon History of the Universe: The comic discusses the concept of selective kindness in talking about inter-cultural relationships in the days before diplomacy: everybody is tender to their own people while at the same time acts callously brutal to everyone else.
Dorian Chief: (doting over his wife while being surrounded by piles of corpses) Oh, did you cut your finger, dear?
Catwoman: Catwoman obviously can't pet a dog without ruining the motif, but she's been subjected to a number of Pet The Cat moments, a prime example being the ending of this web-toon. She's not the least bit disappointed that she wound up saving kitties instead of stealing gemstones.
Deadpool: In the climax of the Drowning Man arc in Deadpool 1997, Deadpool shows us that he's given up on redemption by locking Blind Al in The Box, severely beating Weasel, and... petting Deuce the Devil Dog on the head.
Fantastic Four: Doctor Doom is often a benevolent ruler of Latveria, whatever his treatment of the outside world. For example, his heir is Kristoff Vernard, whom he adopted after Kristoff's mother was killed by his enemy, Zorba Fortunov, while she was talking to Doom (and thus, in Doom's view, under his protection).
Guardians of the Galaxy: Though Thanos is still doubtless a sadistic Galactic Conqueror, his relationship with his adoptive daughter Gamora falls under this. It is consistently shown that he does have an uncharacteristic soft spot for her, to the point of giving Gamora a doll for space Christmas, and while he had no compunctions putting Gamora through Training from Hell and replacing her limbs with cybernetics, it's shown in the 2019 series he did the latter with genuine care (something that shocks Death/Magus in disguise). However, this Pet the Dog behaviour from Thanos actually put Gamora at risk from the Black Order, who weren't happy that some little green tyke they picked up on a war-torn planet was getting more care from their master than them.
Hellboy: Hellboy is a huge demon with enough strength to tear a car in half. He is the badass to end all badasses. As such, his action figure comes with the following props: A six-pack of beer, a revolver, and a... kitty?! Yes, the son of Satan is a cat-lover.
Hellblazer: In Hellblazer: Rise and Fall, after witnessing Thomas slap John for mouthing off to him, Lucifer tells him something that makes Thomas apologize for his abusive behavior towards John, Thomas asking if he wants to bond over a pint later. Lucifer admits he had a pragmatic reason for it, considering Despondeo feeds on despair and John's self-destructive behavior is rooted in his dysfunctional relationship with his dad.
Iron Man: In Iron Man 2004, when Tony Stark is proven innocent and the FBI still charges him with resisting arrest, FBI agent Neil Stretch argues about it again with Nick Fury. Neil Stretch is transferred to the Alaska field office as a result. Neil also tells Tony not to be mad at Pepper Potts because she did not break easily: she was in distress, and he played her like he was trained to do. "You want to be pissed at anyone, be pissed at me."
L.E.G.I.O.N.: Vril Dox has a couple of these. Right before he is raped and killed, he confesses to his unconscious teammates that he really does care about them, but he doesn't really know how to express that. When Lyrissa Mallor dies, he mourns for her, believing that without her, L.E.G.I.O.N. would not have gotten as far as it did. When Vril Dox finally gets to see his son, after Stealth believed that he would become just as controlling as he was of the rest of the group, Vril remembers his father being a controlling jerk, and himself being controlling to the Durlan. So he lets the mother have the child. Awww.
Lobo: Lobo parodies this: he is a relentless killing machine who often kills his bounties instead of capturing them, yet at the same time has a soft spot for "space dolphins". But he did once spare Aquaman's life because he felt he couldn't hurt somebody who loved dolphins as much as he did. He also displays a fondness towards Ryan Choi and is the reason Ryan, as The Atom, is inducted into the JLA, despite Batman's wishes for Ryan to not join.
MAD: This is parodied and even deconstructed in an article on "Compassionate Conservatives." The "compassionate" parts of the conservatives are typically described as hypocritical (deporting all illegal immigrants except for their gardeners) or inconsequential (giving last meals and a choice of an execution method to death row inmates while denying them appeals on DNA evidence.)
Maus. When in Auschwitz, Vladek finds himself called upon to repair a badly damaged boot for a Gestapo officer stationed at the camp. After Vladek actually manages to perform the repair adequately, the Gestapo officer gives him a huge sausage (something that would be a rare treat for a German civilian, and an absolutely priceless treasure in the camp, at that point in the war) for his troubles. When Vladek asks why, the officer just shrugs and says that Vladek did good work on his boot.
Negation: The Saurian party member subverts her pet the Kaliman retriever moment when she names him "tasty treat" in her people's language.
Nemesis the Warlock: Defied when Purity infiltrates the Terminators as Torquemada's new girlfriend (Nemesis used a spell on him) and after spending several weeks seeing how blatantly monstrous he is, wonders if there's anything remotely redeeming about Torquemada so asks him if he likes dogs. Torquemada states he doesn't.
The Punisher: In Punisher War Journal, the Rhino has a few. First, he writes an apology letter to the widow of a cop he had accidentally killed and sends her money with each score he pulls off. Second, in the last issue, he convinces the Punisher to leave the Stilt-Man gang alone (on Christmas, no less) because he could tell they were just stupid, not evil.
The Punisher MAX: In the beginning of Kitchen Irish, Frank is eating lunch in a diner when a bomb goes off in the pub across the street. People all around him get butchered when the diner's large window shatters, and once the debris settle he finds a man whose chest had been shattered, revealing his heart, giving the following Pet the Dog moment from Frank.
Injured Man:help me Castle:[narration] So I do. For no reason I can pin down it becomes very important that this guy makes it. Maybe he has a wife and kids. Maybe he wants to see them again like nothing else on Earth.
Frank works on keeping the man's exposed heart from bleeding out, and when a rookie EMT gets there, they spend an hour working together on the man before finally succeeding in stabilizing him. It takes several more minutes for the traumatized EMT to notice that the man who helped him save an otherwise-doomed life did so with six inches of glass sticking out of his arm — and that he is a mass-murdering vigilante. He treats the wound without another word, and an understanding is silently reached; the EMT will go on saving lives, and the Punisher will track down whoever started a war in downtown New York.
Castle:[narration] Not every day you meet your polar opposite.
Crossing over with Real Life, one autobiographical comic story details the summer the author spent working in a restaurant run by the tyrannical butcher Yarborough, who would, almost every day, take out his frustrations on Francis, a deaf-mute waitress with a cyst on her breast, usually with the same rants of "YOU DUMMY! GOD DAMN YOUR SOUL, YOU DUMMY YOU!" Years after he quit, the author runs into his replacement who tells him that Yarborough died a few years ago... and left Francis enough money to set her up for life.
Doctor Octopus has gotten a few Pet the Dog moments over the decades, including trying to save Aunt May from Hammerhead and trying to develop a cure for AIDS in order to save his ex-girlfriend.
Depending on the WriterGreen Goblin (especially earlier on) shows some genuine love for Harry his son, averted greatly in other comics though.
In Spider-Man Family #4, the Fantastic Four villain named the Puppet Master meets a young boy named Louis, and not only comforts him when he's picked on by bullies, he gives him the Spider-Man doll he was making to use in one of his evil schemes, willingly abandoning one of his evil plans to comfort a distraught boy he has only know for a few minutes.
Spider-Men II: It's a bit rare to see the Kingpin having a friend, and not betray him, use him, or pretend friendship in order to gain something. The adult Miles Morales is truly a friend, and he actually cares about him.
In Superman/Supergirl: Maelstrom, Darkseid takes time to explain Maelstrom personally he doesn't and won't reciprocate her feelings. By his standards, he is being practically kind and straightforward.
In The Supergirl-Batgirl Plot, Mr. Mxyzptlk and Batmite come together to prank Superman, Batman, Supergirl, Robin and Batgirl. After having plenty fun at the expense of the heroes, Batmite tricks Mxyzptlk into returning his dimension, fixes the mess they caused and leaves on his own.
Touch (2004): No one who knew Dex well has much good to say about him except for Diego, a Heroic Wannabe and Sci-Fi geek who hangs outside Supernova Solutions and mentions Dex would buy him fast food sometimes.
Ultimate Spider-Man (2000): When Nick Fury first meets Miles Morales, who's hated by just about everyone else at the time, he talks to the boy. When in danger, he escorts him by hand to what he thought to be safety. After Miles proves himself, he gives him a new costume (oddly the one Miles was hoping to design himself) and allows him to be Spider-Man.
The Walking Dead: Negan is a sadistic monster that likes violence but in Issue #105 instead of killing Carl for shooting at his men, Negan instead had a civil conversation with him and he even apologized for hurting Carl's feelings when he brought up the issue regarding Carl's eye.
Edward Blake aka The Comedian in Watchmen has a couple of moments like this. The first is when he is talking to a teenaged Laurie and tilts her chin up to look at her eyes, which he says are like her mother's. It turns out that she's his daughter, and he looks a little sad when Sally Jupiter drags her daughter away from him. The second instance of this for him is when he cries after finding out about Adrian Veidt's plan to achieve world peace by killing millions worldwide. He even cries when talking about this to an old archenemy, who he says is "the closest thing I have to a friend." Considering that Blake has several instances where he could be said to cross the Moral Event Horizon, these moments are probably sorely needed for his character.
Rorschach is an alt-right wing brutal Vigilante Man and Nominal Hero but he does have some true altruistic and compassionate moments in the comic. When confronting his hooker landlady who made false allegations that he tried to assault her, he reveals her profession and is about to rip into her but when he sees he’s scaring her children, Rorschach looks upon the kids with genuine pity (likely remembering his own similar childhood) and leaves them alone. He also shows care towards Dan Dreiberg/Nite Owl II who he admits is probably his only friend and despite not getting along with Laurie (he horribly dismissed Comedian almost raping her mother), he respectfully addresses her as “Ms. Juspeczyk” (rather than Jupiter) when she and Dan break him out of prison. Additionally for all Rorschach‘s misogynistic beliefs, he is shown saving a woman from being raped by a street thug and has killed numerous sex offenders.
Adrian Veidt aka Ozymandias has more a literal example of this (just a feline instead of a dog) as while he is the kind of man who would kill three million people to create world peace, he does seem to like and often pets his genetically altered lynx Bubastis… though he was still not above atomising her while trying to kill Doctor Manhattan. At most apologising to his big cat as he did it.
White Tiger: Ayala allowed her sister-in-law Soledad in her house, and it is implied that she is supporting her throughout her depression after her brother's death. Despite the fact that Soledad intended to file for divorce immediately after her husband White Tiger (Hector Ayala) was wrongfully arrested for murder, because Hector had promised her he'd give up being a superhero. And part of the reason Hector had a break down after he was convicted was because during the trial, when the prosecuter questioned their marriage, she couldn't stand the pressure and left the courthouse. Despite all that, Ayala does not hold that against Soledad and still helps her. When Ayala's son Rey protests allowing Soledad in their house after how she treated Hector during his trial, she states that Soledad is Hector's widow, she's family, and she has not been well since Hector's death.
Logan gets this from Lady Deathstrike in one issue of Wolverine (1988) during the "no adamantium" arc, when she learns the metal's gone.
[Logan retracts his claws, letting Deathstrike see him bleed from the holes in his hands] Deathstrike: You're...still bleeding. But your healing factor— Logan: It's pretty much used up. As good as gone. [Deathstrike hesitantly brushes Logan's forehead with one finger] Logan: [internal] For the first time in years, she reaches out to touch me...and the touch is gentle.
Wolverine's son Daken is a murderous, manipulative sociopath and Anti-Villain. However, he does have a genuine soft spot for his little sister Laura and her 13-year-old clone Gabby. In All-New Wolverine, he comes to Roosevelt Island not to save lives, but simply because Laura wants him to be there.
Laura: Daken? You came to help? Daken: I did. But I'm not here for the island. Laura:[hugs him] Thank you.
In Judgment In Infinity, the Adjudicator's overseers may not care about Earth, but they do not actively wish harm upon humans either, so they teleport all heroines back to their respective Earths when they take the Adjudicator away.
Wonder Woman (1987): When Athena had her champion Diana, who was blind and recovering from serious injuries at the time, fight against Zeus' champion, the Hekatonkheires, Ares strolled in to try and interfere. While he was stopped by Aphrodite he still made biting comments at Athena to try and get her to aid her champion, he'd helped Diana before but never so openly and without an apparent plot to benefit himself in the works.
When Cassie lost her powers, Ares offered to restore them. Instead of a Deal with the Devil, all he wanted in return was for her to call him and consider him her brother. Though this was kind of subverted when it turned out that his powers were driving her crazy he may not have been aware of how it would affect her.
X-Force: X-Force (2008)'' deconstructs this trope in Eli Bard's backstory. He was a Roman senator named Eliphas who was regarded as a push-over by his family and peers, but he had a Morality Pet in form of a little girl that served as a slave. When he crossed paths with Selene, she offered to love him forever and make him immortal if he sacrificed every soul in Rome to her. Eliphas agreed to do it, but decided to warn the little girl to leave the city with her family. She told her parents, who proceeded to warn the guards about him, who interrupted him just in time he was about to perform the spell to sacrifice all Romans. This led to him getting cursed by Selene and turned into a vampire-like mutate, living in constant torment for not being together with his beloved. In short, after he took the path to evil, his one moment of kindness cost him everything.
While Emma Frost is still a bitch after joining the team, she gets more than enough Pet the Dog moments around X-23/Laura Kinney. While at first seemingly hostile to the younger girl due to her being a female clone of Wolverine that was created solely as an assassin. It's eventually revealed that this is because Emma see's the same capacity to hurt others in Laura that she had when she was younger with the main difference being that the latter has no choice in the matter due to her conditioning to a "trigger scent" (which sends X into a berserker rage). Later on, we see Emma eventually warm up to Laura to the point where whenever whenever we see Emma in one of X-23's books, it more often than not involves her lamenting on how they've failed to treat her right. Emma goes into full Mama Bear mode when Kimura tries to kill X-23. Emma psychically immobilizes Kimura then points out exactly why she enjoys hurting X (her own bad childhood), before proceeding to erase her only happy childhood memory and then sending her off to kill the people who sent he to kill Laura in the first place.
Sabretooth has had his share of these over the years, but Weapon X (2017) has the closest literal example: a baby tiger he takes a liking to. There's also the instance of him saving his son Graydon from Hell in the same series.
Chaotic Evil Card-Carrying Villain like the Joker does these every now and then. One issue of Deathstroke had him rescuing a small girl from her abusive Sleazy Politician father (setting her up to go live with her mom instead) at absolutely no apparent gain to himself (well, okay, he "rescued" her by poisoning the city's blood banks and using that to coerce the politician, but if that was all he wanted he could've just gone ahead and done it; after the girl's safe, he even leaves the antidote behind!).
. She's not the least bit disappointed that she wound up saving kitties instead of stealing gemstones.