Heroic BSOD - If this is your superpower, you're in trouble.
Rick from The Walking Dead has too many of these to count, most notably after Lori and Judith die escaping the prison.
Tails suffer this in the Sonic the Hedgehog comics when he finds out Fiona Fox, his crush, was a traitor and was cheating on Sonic for his negative counterpart Scourge, going to his side for the thrill of being bad, and as if things weren't bad enough for him, she tells him off with a "You can't trust anyone." And she promptly slaps him several feet away, leaving him a confused, crying mess.
Sonic himself had one when his girlfriend is roboticized, the evil Ixis Naugus becomes king, the Babylon Rouges get away after endangering his city For Science!, Antione makes a Heroic Sacrifice that saves Sonic's life (whom of which he wasn't exactly the nicest person to) and Bunnie runs away from feeling useless due to her recent derobotization. He's gotten better though.
Sally suffered one following her watching Sonic pull off a seeming Heroic Sacrifice. It got worse after Sonic came back and he was STILL fighting Eggman. This lead to the infamous slap.
Strongbow the elf archer loses his will (and consequently ability) to use his bow after making the traumatic decision to kill an elf who attempted to kill his son (up until that point in 10000 years of elf history, no elf had ever killed another elf, barring numerous threats and a couple of failed attempts). Only after he is able to connect with his victim's spirit and beg its forgiveness does he return to his old self.
Clearbrook also suffers a Heroic BSOD after her lifemate One-Eye dies, but forces herself to keep fighting once the next battle starts.
In Animal Man, Buddy Baker has a BSOD lasting at least several days when an assassin murders his wife and children. This subverts temporarily the normal tendency of Dark Age superheroes to immediately go on a Roaring Rampage of Revenge.
In Runaways, Victor Mancha, a cyborg, goes into what characters describe as a Blue Screen of Death when he hears three pre-determined questions that conflict with his logic programming and spirituality. Only one has been used (Q: Could God make a sandwich so big, he could not eat it? A: Yes, and then he would finish it anyway.), but Chase mentioned that there are three questions in total. However, each question only works once.
The quote above from Preacher is taken from the All In The FamilyStory Arc, where one of the villains comments on the eponymous protagonist's Heroic BSOD, after he saw his lover shot dead right in front of him.
"Boy looks like he took a shit and found his liver in the bowl".
The eponymous character of The Desert Peach (Erwin Rommel's brother) suffers one (complete with "Attempting reboot" comment) after some men in his army unit give him some compelling evidence about the implementation of Hitler's Final Solution.
Nightwing has an enormous BSOD after a series of events including an attack on Oracle, who proceeds to dump him; his circus, which was burned down; his apartment building being bombed that culminates in the death of a certain villain, and he plunges further into mind breakage when he's subsequently raped by his particularlydisturbed accessory to the death of said villain.
He also had a milder one after the Crisis Crossover where he nearly killed the Joker.
Has one of these in the Elseworlds series The Nail (set in a world where Superman was not raised by the Kents) when he kills the Joker after being forced to witness the Joker's extremely sadistic double murder of Robin and Batgirl. He makes it back to the Batcave but is catatonic until Catwoman (who did a Heel-Face Turn to help him against the Joker) puts on the Robin costume and shocks him out of it.
He also has a mild BSOD after the death of Superman, making it easier for Bane to wear him down.
Catwoman has a rather bad one after her sister is forced to watch her husband tortured into insanity by the Black Mask. Holly has a similar one at the same time after killing Selina's friend.
Cyclops, in Joss Whedon's Astonishing X-Men run, has a severe one of these when Emma Frost reveals to him that his inability to control his powers is the result of a complex he developed about self-control as teenager, rather than a brain injury resulting from a concussion, as he had previously believed. He spends and issue or two in a completely catatonic state, his powers not functioning. He soon recovers enough to move around and lead the team (perhaps even more effectively than usual, with his self-control issues out of the way) and later surprises everyone by revealing (with a point blank blast in the face of his interrogator) that his powers still work, and that he now has full control over them. At the end of the arc, this control fades as the "clarity" he got from Emma's intervention wears off. See Status Quo is God.
The title character has one of these in Cerebus the Aardvark after witnessing what he believed to be the death of his love interest: Jaka. He spends several issues hanging out in a dinner/inn while in a near-catatonic state until somebody pushes his Berserk Button.
Spider-Man is a master of this. The death of Gwen Stacy is the best and most famous example. In Clone Saga it happens one time after another and the level of his Wangst is just ridiculously big.
Superior Spider-Man is hit with this in issue #29 when the Goblin King makes his move on Spider-Island, leaving him utterly speechless and unable to move his men.
In Conan the Barbarian #197, Red Sonja had one following her defeat by the warlord Bakht. Despite the ambush tactics and magical aid Bakht received during the battle, Sonja was so severely injured that she became convinced that she had lost her divine gift for combat. She was back to her old-self by the end of Conan #200, after a confrontation which forced her to fight back or die proved that she still had her skills.
In Superman/Batman: The Search For K, Superman fell to his knees in despair when he and Batman found out that the squad armed to the teeth with kryptonite weapons and out for Supes' blood was created, funded, and sanctioned by the US Government itself. They don't give a crap about Superman's heroism and devotion to protecting the people, and want him dead. Oh, and Lex Luthor had nothing to do with this, either. He bounces back in spectacular asskicking fashion when Batman says that he believes in him.
Downplayed with Swamp Thing. He has a brief one in the first arc of Alan Moore's legendary run, after he learns that he isn't Alec Holland turned into a plant, but a plant that absorbed the deceased Alec Holland's memories. His BSOD lasts one issue and ends with him accepting his true nature, so as to ensure that the series didn't bog itself down in the Wangst of Swamp Thing (already a serial moper) moping about because he was a literal monster and never Alec Holland to begin with.
Cassie Hack of Hack/Slash went through one (entering what was an Angst Coma to boot) after the Reanimator, in which her long-lost father dies, and she's forced to kill her mother (... again).
Two at the end of Vol 5 of Empowered, right after another. Sistah Spooky snaps upon being just a few seconds too late to save Mind????, something her powers warned her about but she didn't recognize the significance of at the time. Immediately afterwards, Emp breaks down as well, explaining to a murderous Sistah Spooky that if she had only been just a little bit more confident, maybe Mind???? would have let her try using her powers to survive re-entry into Earth's atmosphere.
The Punisher suffers one of these in a MAX comic after believing that he shot and killed a young girl. He nearly kills himself over it, until discovering that she was already dead and he was set up.
Actually the same plotline occurred years earlier in the main series, with Bullseye having killed a family of tourists in the same way. Unlike the MAX one which lasted a single issue this BSOD (after a short buildup period where he went on one last rampage) had Frank fall into a complete catatonic state which he was pulled out of by brainwashing which sent him on a rampage of killing drunk drivers and litterers before seemingly killing Nick Fury. He then fell back into it and plead guilty to the murders, not breaking out until Bullseye revealed the ruse to him on the eve of his execution.
Furthermore Frank's poor mental state makes this fairly common, by my count he's had four in the main Marvel universe and two in the MAX continuity (the second of which is still going circa April 2011)
The Flash suffers an extended one due to the course of events over the Blitz story arc. A good friend turns nemesis Zoom, hospitalizing Flash's wife and killing his unborn children. The villain's permanently faster than Flash, exhausting the hero just trying to keep up. Three of the Flash family lose their powers trying to help, one permanently. At the end, the Flash stops Zoom, only to fall to his knees in horror at the realization that all he's gained from "saving the day" is a lost friend, weakened allies, and an uncertain future with his wife. Meanwhile, the next villain to come along gets to pick up where Zoom left off.
Another famous one was in the "Return of Barry Allen" arc. When his own hero seemingly has a BSOD of his own and then apparently commits one huge Face-Heel Turn and leaves him for dead, Wally loses his all his beliefs, throws his costume away, and shuts himself off from the rest of the world. Only the discovery that "Barry" is actually the original Zoom is enough to shake him out of it.
Scott Pilgrim gets one at the end of Book 5 and for more than half of Book 6 when Ramona leaves. His friends try various ways to break him out of it, but in the end, he has to confront his desire to forget his mistakes and jerkassedness before he can recover.
In Final Crisis Aftermath: Dance, features each member of the Super Young Team going through one of these at one point or another. Well-Spoken Sonic Lightning Flash has his when the team splits up, walking aimlessly and endlessly through the desert, while Big Atomic Lantern Boy's comes when Shiny Happy Aquazon explicitly turns him down for the first time.
In Echo, Ivy Raven had more than a few rough spots throughout the series, but when she woke up and did not remember the story she began to break down.
Ivy: "I need to know...Julie, I woke up and I couldn't remember..." Julie: "Remember what?" Ivy: "Anything! I didn't know where I was, how I got here...I've been telling myself these changes to our bodies are just external but, I don't know. What if it's affecting our minds, too?"
In Immortal Iron Fist's Seven Deadly Weapons spin-off mini, Fat Cobra meets with the writer from whom he'd commissioned a biography. Fat Cobra has, through the power of chi, lived a very long time - and through the power of alcohol and concussions, has forgotten much of his life beyond the past decade or so. During their discussion, he learns just how he became the Cobra Warrior of Peng Lai; he slept with many women and had scores of children. Those children grew into adulthood and sought revenge on their deadbeat father. They came for him. He killed them, in so doing growing more powerful than he ever had before, strong enough to finally claim the title of Cobra Warrior. Upon discovering this, he has his biography burned and dismisses his company. He glares at the fireplace in disgust as he sits alone.
The Boys is about a group of superpowered CIA operatives who provide a balance of power for rampant "Super Hero" groups, (who either do nothing but live as celebrities while indulging every sick whim, no matter who gets hurt, or are villains with good publicity that you should really be wary of) and the Mega Corp. behind them that eventually wants to turns supers into living weapons. In one arc, The Seven, (the most powerful of the super hero groups and essentially the Justice League of America) and The Boys nearly get into a showdown when a member of the Seven is Caught on Tape. At the last moment, the Seven realize that Butcher, the leader of The Boys, is telling the truth when he says that they didn't release the tape. The member of the Seven who was on the tape flies off in a huff, and everyone walks away, until Butcher goes back downstairs and sees that his beloved dog Terror is dead. Butcher walks right out to where he knows that one member of The Seven will be, catches the guy by surprise, and begins stabbing him over and over, repeatedly asking "Why'd you kill my dog, Jack?". At one point Jack tries to say something or maybe beg for mercy, but Butcher says something along the lines of how his mind isn't really even there, it's just watching what he's doing from somewhere far away. Then he goes back to the stabbing and questioning, over and over, long after Jack is dead.
In New X-Men, all of the students have one when a bus full of depowered mutants is blown up right in front of them. Especially evident in Hellion, Elixer and Surge.
Twilight: Maybe I've been wrong this whole time... The magic of friendship can't save everything... It couldn't save Spike.
In Zot!, Jenny has a major one after 9-Jack-9 kills the president's daughter, Susan. Zot himself has one as well, but manages to hold it off until after bringing Jenny to Woody's house, telling him to take care of her.
Superman suffered one early in his Post-Crisis career. After being dragged into another dimension to deal with three alternate universe Kryptonian criminals who had practically wiped all life from Earth, Superman is forced to execute them as there would be no other way to bring them to justice on his world. The decision causes him to have a breakdown and start sleepwalking... well, sleepvigilante as Gangbuster until the Guardian snapped him out of it. Supes was so horrified by what he had done, he exiled himself from the Earth and stayed that way until he could confront his demons.
Meriem experiences one in Cavewoman: Primal when she believes Bruce is dead. She charges into the jungle in a dinosaur-slaying frenzy, seemingly trying to get herself killed.
X-23 is constantly slipping in and out of these. When first introduced in NYX she's virtually mute, and in her first few panels she seems as if she's barely aware of what's going on around her. Then we learn in Innocence Lost and Target: X just whatput her into that state. In fact, in the latter book she's broken so completely she's gone outright Death Seeker, intending to kill Wolverine and herself. She goes into another in the third arc of her solo series when she accidentally attacks Gambit, and spends the rest of the day and well into the night curled up in bed staring at her claws with Gambit sitting vigil over her. By the time she turns up in All-New X-Men she's in yet another one, due to the 1-2 punch of what happened to her on Murderworld and shortly after being captured and tortured by the Purifiers, leaving her wandering the streets of Miami in an amnesiac state.