Jess hates it when other people defend/are nice to Tess. For example, when Daisy tells her to back off and leave Tess alone, she bitterly barks at her to "shut the fuck up". She later punches Lucy when the latter calls her out for trying to manipulate Paulo to dump Tess. This turns out to be semi justified, as Tess ruined her life in the past.
Several College Roomies from Hell!!! characters have Berserk Buttons, but the most dangerous is Marsha's. She will try to kill any of her ex-boyfriends on sight — and God help her current boyfriend if she gets it in her head that he's cheating.
Justin has one in regards to his ex-girlfriend who accidentally outed him as gay and then went Stalker with a Crush on him.
Chaos generally refuses to interfere with anything, both because she's not allowed to and because its more fun that way. When someone hurt her son though, not only did she do everything in her power to get him killed, but she then decided to destroy the world and remake it into something her son would be more comfortable with. She hasn't quite managed that yet, but her son is quite justifiably freaking out.
Everyday Heroes has Violet Klein (aka "Shrinking Violent") who is sensitive about the size of her nose. If anyone bumps into it, she undergoes a transformation parodying The Incredible Hulk only in reverse. She shrinks down from 7'2" to 2'7" and goes violent until someone can bring her candy to binge on. This returns her to her normal state but is dangerous, because she's diabetic and could die from the sugar rush.
The Jaegers of Girl Genius are all very, very fond of their hats (a common Jaeger remark is "Hey, nice hat!") and, apparently, take it badly if the hat is mistreated. When Agatha knocks off Maxim's hat (because he was being rude) he's very much about to flip out... except Agatha is currently in her mad-girl mindset and promptly puts him in his place.
When Lars was killed, Agatha flipped out, and if you know she's a girl who can build a Humongous Mecha in her sleep, you'll understand why this is bad.
Antimony is generally calm and helpful, but when people say bad things about her father she... does not take it especially well. After Sir Eglamore voiced such a notion, she set him up to look as more incompetent and violent than he is before his friends, and added some long-term hostility for good measure. Later, when Renard badmouths her father while berating her about her homework. In a fit of cold fury, she lets slip that Surma never loved him. And continues to twist the knife with a look of vicious glee on her face. Beware the Nice Ones, indeed. (And then Zimmy intentionally used it as a nightmare catapult while in mental contact with Annie. Judging by her face, she didn't expect the "catapult" part to be literal, though. Annie is powerful even when out cold in the infirmary.)
For Kat, it's doing anything to hurt Annie, even if it's hurting her feelings. She punched a Psychopomp when she learned that none of them came for Annie's mum, forcing Annie to do it herself. Later she chewed out another Grim Reaper affiliate who snapped at Annie for not doing that job "properly" and told him to get out of his own room... which he did.
After Becquerel's self-prototyping, Jack gains all of the "devilbeast's" powers as well as his adoration and loyalty to Jade. Unfortunately for the Courtyard Droll, killing Jade with a shaving cream bomb before Jack's eyes wasn't the best thing he could have done.
Ironically enough, Gamzee's Berserk Button seems to be the "Miracles" music video.
There are very few things that can make Dave lose his cool. His sister's life being in danger is one of them.
John goes absolutely apeshit in Act 6 when Davesprite mocks his dead father's So Proud of You notes, and starts looking for a hammer.
Meenah flips out when she discovers her post-Scratch self was being manipulated by Lord English rather than just rocking out as an evil bitch-empress and begins screaming vows to gild his skull and keep it as a trophy.
Mentioning Solid Snake or Liquid's "inferior recessive genes" will throw him into a rage. Weaponized by Psycho Mantis: "If anyone can verbally assault Liquid cruelly enough to save him, I can.''
Psycho Mantis has quite a lot of them. Women, sex, stupidity, ghosts, stealing his coffee... For him and Revolver Ocelot, their berserk buttons are each other. Berthold will rip out your lungs if you bother Sniper Wolf. Naomi goes nuts if you say anything bad about Gray Fox. Raven goes nuts if you say anything "racist" around him. Most named characters have berserk buttons.
Namor: This is what you get when you provoke my insecurities! Sure I might dress a little provocatively and sure, my hair is always silky and fabulous, but that's no reason to assume anyhting! I'm Namor the womanizer supreme! The prick with a huge dick!
Referred to in the Narbonic fanfic "A Brief Moment of Culture":
There are some things you can't say to people around here without having them come completely unglued. With Helen, it's, "Well, it looks like those fools at the institute were right after all!" All it takes with Dave is, "Bad news, all they had left was menthol." And Mell? Well... "Your weapons are useless against it!"
Naturally, Artie doesn't tell us what, if anything, is his own Berserk Button. After all, he is superintelligent.
Noblesse Frankenstain has a soft berserk button set off by messes & property damage, & a hard berserk button that goes off if he feels you are disrespecting his master or if you force Raizel to use his powers. Rael's berserk button is anyone but him flirting with Seira. Regis can trigger anyone's berserk button by describing at length how ineligant they are. Lastly the Clan Leaders have a shared berserk button set off when Karias addresses the Lord casually, like calling her "Nunim."
In Nodwick, do NOT make Piffany cry: Artax and Yeager will kill you.
In the web comic Nosfera, threatening or harming either Nosfera or Grimsworth in the other's presence is a really good way to get yourself killed.
Also trying to match Xykon in arcane power and getting sort of close. This irritates him so much that... he stops goofing around and will roflstomp you, even taking advice from subordinates in order to make sure you die.
Causing Xykon to lose his phylactery will make him furious, to the point of dropping all acts of politeness and trying to outright kill you.
And Vaarsuvius. Normally bored and apathetic, but threaten his/her family and he/she will brutally and gleefully slaughter you then revive your HEAD and use it as the focus of a spell that wipes out YOU, ANYONE RELATED TO YOU, AND ANYONE RELATED TO THEM. "This — and no less — is the price for threatening my family. Disintegrate."
S/he was recently given a (much) more mild example. Do not call him/her a Warlock unless you want a quickened lightning bolt to the face.
Sakana. If you do something to hurt Jiro or even just talk bad about him, his big brother Taro WILL hurt you. Also, if you mention the fact that Jiro is more successful at being a register worker in front of Yuudai, things will get ugly. Really ugly.
Oasis from two of these. Identify yourself as a HeretiCorp employee or the object of Torg's love, and she will kill you painfully. The first is the result of extensive brainwashing, but the second is pure jealousy.
Bun-bun the mini-lop can be set off just by being. Period. However, if you really want to make him go so far as to take over a spy organization just to hunt you across half the world so that he can kill you, just mess with his Baywatch tapes. His button was probably pushed and then broken off about the time he was born.
One berserk button that steers into major Narm territory is the button for Sonichu's Rosechu: hit her with a pickle, and she'll strip out of her clothes and face rape you. Yes.
Spinnerette: The titular six-armed hero hears cracks about her deodorant bill several times a month and responds with anger when they bring it up, insisting that they should be more original.
From the same comic, Tiger has several: being called Black Tiger, implying that his muscles were gained through steroids instead of training and protein shakes, and his blind hatred of Canadians. Though he has gotten better about the last one.
In Supernormal Step, Derry, as a Mood-Swinger, gets angry at the mere mention of Henderson Security, but he loses it completely when Fiona mentions that the Hendersons made her an offer, and he gets even angrier when Hall rescues her.
Shiratz in UNA Frontiers really, REALLY didn't like it when his last "owner" in the late pre-Burn era was kidnapped, tortured and murdered. Said persons wound up as barely-recognizable human remains beneath his hooves.
In Wapsi Square, Jin went berserk when she caught a rape-in-progress.
Waterworks: The protagonist, Connie, is fairly germophobic, and she goes for an off-screen Extreme Melee Revenge after being splashed with what she thinks could be toilet water.
Doc from The Whiteboard is a stickler for proper equipment usage, safety, and maintenance. Given some of the inane or outright stupid customer requests he's had to deal with over the years, it's an understandable peeve, but it does seem kinda strange coming from a guy who's shop explodes several times a week. But then again, there's probably a good reason Doc's hobbies haven't killed him yet.
Yamara as a halfling and thief seems to be accustomed to some people's disdain, but ones who miss her multiclassing while showing it provoke her to make a point. It isn't Unstoppable Rage, but they just earned a ticket to the world of hurt, one way or another.
In Zodiac, if you value your health, DO NOT call Taurus fat.
When around Fighter of 8-Bit Theater, even if you're a teammate, under no circumstances are you to threaten or even imply that you will, either through action or inaction, bring harm to Black Mage. That would be wrong. Kind of chainsaw wrong.
idol3341: GRAAAH!!! I HATE YOU!! YOU SON OF #@*!!!
Also, whatever you do, DO NOT call idol small. Just don't. A stranger learned it the hard way when he called her small. But it was only a fantasy. In real life, idol, angered, says, "If only I had a gun..."
idol3341 even said that she drew this with all her fury because she was so angry about the "idiots" on the streets.
idol3341: Lately are more and more idiots in the streets and i was so angry that i draw this with all my fury XD
This comic also has idol's many other Berserk Buttons, such as hating the flute. Also, as idol says in one of her facts, don't come near her when she's mad.