The feud Edge had with The Undertaker in 2008. He went from a rather calm and collected fellow to an Ax-Crazy raving lunatic. Edge performed the breakdown without any assistance from The Undertaker at all, when some Laser-Guided Karma caught up to him when he cheated the recently drafted to RAW Batista out of the World Heavyweight Title. The next night on RAW he interrupted the farewell speech of the recently drafted Jim Ross to put himself in the spotlight, mocking the superstars of RAW by pointing out that the red brand no longer had a world title (WWE Champion Triple H had been drafted to Smack Down the previous week), then stating that they would never see him on RAW again. Just as he was leaving however, an understandably angry Batista appeared and proceeded to give Edge a well-deserved No-Holds-Barred Beatdown, ending with a Batista Bomb in the middle of the ring. Not long afterwards, recently drafted to RAW Mr. Money in the Bank CM Punk (who would later on become the second man to cash in the MiTB briefcase after Edge himself) appeared, cashed in the case, and proceeded to win his first world title. Edge lost it and ended his engagement to Vickie Guerrero, though they eventually got back together. Then, towards the end of the wedding reception three weeks later, Triple H revealed that Edge had cheated on Vickie with their wedding planner, future WWE diva Alicia Fox. Vickie got mad, mad enough that she reinstated the Undertaker, even so far as pitting them against each other in a Hell in a Cell match at SummerSlam. Edge freaked, before driving himself into becoming completely unhinged, only to lose against 'Taker and sent to hell, disappearing for three straight months before reappearing at Survivor Series later that year.
Eddie Guerrero used this as part of a Face-Heel Turn in 2005. He claimed to be the biological father of Rey Mysterio Jr's son, Dominic, among other things. It was truly a sight to behold, since Eddie had been a face for so long that he had to nearly take Rey's head off to get fans to boo him.
Vickie Guerrero gets one when Edge gets her fired after she abused her power to make his life a living nightmare. She breaks down in tears and starts begging everyone, even a cameraman to help get her job back. She finally ends up begging at Edge's feet for him to help her. He doesn't listen. On the July 8, 2013 episode of RAW, Guerrero does another one, throwing a fit after she was "fired" by Stephanie McMahon.
Hulk Hogan has been showing signs of this since "the network" began interfering with his Immortal stable's domination of TNA. While he puts on a facade of a Smug Snake in the ring, a backstage scene had him in a paranoid rage over the networks interfering, claiming they "know too much" about how wrestling works and demanding Eric do something about it. It's been getting worse each week and Eric has also began to head into a Villainous Breakdown of his own for the same reason.
Michael Cole has one on the April 11th Raw. After Jerry Lawler defeats Jack Swagger, earning himself a match at Extreme Rules 2011 with Cole, with Jerry choosing the match, Cole, for the first time in weeks, is left completely speechless. After a few minutes of silence, he snaps and explodes on his Dragon Jack Swagger, blaming him for everything and slapping him. This instantly comes back to bite him when Jerry reveals their match will be a tag team match, and Cole's partner is the man he just ticked off.
Had another one on the July 27, 2011 episode when Triple H reveals he'd rehired Jim Ross. Michael goes on a major tangent, screaming his head off about how he refused to work with Ross at all. Too bad for him, Triple H was already about nine steps ahead of him and knew he'd probably do that.
On the May 23, 2011 episode of Raw, Kharma, a monster heel Diva who had been tormenting and bullying the Divas for weeks, comes out to the ring as per usual. But this time, she finds the entire Divas locker room surrounding her, having been fed up with her attacks, showing no fear. While confident at first, she breaks down in tears and has an emotional breakdown when she realizes they no longer fear her and she can't beat all of them at once. The announcers even refer to it as a breakdown afterwards.
Actually, that wasn't the reason why she had that breakdown. In the next week, she reveals that she's pregnant and will be out of action for about a year. She gains sympathy from the audience as she talks about how she made it here in WWE.
CM Punk has one on the July 11, 2011 episode of Raw. After showing his Magnificent Bastard self the whole night, John Cena comes out and gives Punk a perfect Kirk Summation, calling Punk out on his chronic Hypocrite status and asking him an Armor-Piercing Question: if you care so much about the WWE Universe, why are you walking out on them? Punk's response is to get furious and try to find something to one up Cena's arguement, but his comeback ultimately devolves into trying to pin his leaving on John Cena, which due to the contract he had wrote up, no longer makes any sense because he'd been offered everything he'd wanted that Cena had on a silver platter and kept Moving The Goal Posts (something Cena had already called him out on), supporting Cena's point of him being a Hypocrite instead of countering it. He ultimately tears up the contract in anger, doing exactly what Cena was calling him out on.
He has another one in January 2013 after his loss of the WWE Championship to The Rock. He went absolutely ballistic the next night on Raw, outright screaming at the fans in attendance and attacking everyone at ringside. Far as he's concerned, he's still the champion.
CM Punk, himself an earlier victim of a breakdown in 2011 (see above), causes Executive Vice President of Talent Relations and Interim Raw General Manager John Laurinaitis to suffer one hell of a breakdown, as he unleashed the mother of all "The Reason You Suck" Speeches to the guy on the January 16, 2012 edition of Raw.
Vince McMahon infamously suffered a breakdown in 2007 after losing the ECW Championship at One Night Stand 2007note Though one could argue it began after his hair was shaved at WrestleMania by Donald Trump, with Vince acting increasingly erratic in following weeks. This ultimately culminated on a Raw that was billed as "Vince McMahon Appreciation Night", where the complete opposite happened and anyone and everyone got their shots in on Vince. The night would end his "death" after his limousine explodednote Of course, the untimely Chris Benoit incident put the kibosh on the angle before it could truly continue on.
On the account of failing to win the WWE Championship on several occasions, as well as being left at the altar by (eventual Raw General Manager) AJ Lee, Daniel Bryan had spiraled into a breakdown of unimagined proportions in 2012, snapping at fans for "stealing" his signature Big "YES!" chants, and instead embracing "NO! NO! NO!" as his catchphrase.
After messing with Zack Ryder to get what she wants, Manipulative BitchEve Torres tells the Bella Twins to record her sucking up to John Cena and use him like she did with Ryder. But the Bella Twins look a bit nervous about what she said and refuse the offer. So she turns around...and there's Cena, who had heard the entire thing. Later that night, she comes out to him and pretends to be upset about him rejecting her, but Cena sees through this act and calls her out, roaring "I lost a broski to a hoeski!" And when she starts to throw herself at him, he gets her away by saying this:
John Cena: For your information, I'm disease-free. I'd like to keep it that way!
Whenever one of his guys would lose championships or fail to beat Hulk Hogan, Bobby "The Brain" Heenan would always suffer a meltdown and rant and rave about how he's been robbed and make up all sorts of excuses about what happened. A spectacular one came at WrestleMania VIII (1992) when "Macho Man" Randy Savage rallied back against Ric Flair and Heenan goes from smug and confident to breaking down and panicking with each blow The Macho Man connected and losing it when Savage uses one of Flair's own tricks (hooking the trunks) to win the WWE Championship (then called the WWF Championship).
On the July 26, 2013 episode of WWE SmackDown!', Damien Sandow threw a temper tantrum after his former BFF Cody Rhodes threw his Money in the Bank briefcase for a future World Heavyweight Championship match into the Gulf of Mexico.
Both Triple H and Stephanie McMahon went through one during the 3/10/14 broadcast of RAW when Daniel Bryan staged an Occupy Raw protest in the ring with his fans in order to get HHH to accept a match with him at Wrestlemania 30. Stephanie goes ballistic and orders Bryan and the fans to leave the ring to no avail. After repeated attempts to keep the show going, Triple H then finally agrees to the match, only for Bryan to reveal his second demand: If he beats Hunter at Wrestlemania, he'll be added to the title match with Randy Orton and Batista. Cue Triple H completely losing his shit as he has to held back by security to avoid him tearing Bryan's head off.