One of the key reasons for the WWE's success and longevity is the relationship it has with its fan base. Few other forms of entertainment, sports or otherwise, are as interactive with their fans as the WWE is.
The WWE Universe may openly complain about the product on a regular basis, but deep down, the fans love the product and will continue to support it no matter what.
Occasionally, however, that passion can spill over a little bit, and whether it's a few too many beers at a house show, sheer anger at a booking decision, or just the desire to get your face on television, fans have invaded the WWE ring, causing disruptions and carnage.
Not all invasions are unwanted though, of course, with the WWE occasionally inviting fans into the ring to partake in the programme themselves.
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With that in mind, let's take a look back at 7 occasions where the WWE Universe, invited or uninvited, have invaded the WWE ring.
#7: A new member of The Shield
If you're going to be crazy/stupid enough to invade a WWE ring, then picking the right time to do it is key, and in fairness to a fan in Houston, he couldn't have timed his any better.
At the start of a six-man tag-team match between The Shield and The Wyatt Family at Night of Champions 2015, Roman Reigns and Dean Ambrose were set to unveil their third partner, when a fan, dressed in Sheild attire, slid into the ring and stood with the other two members.
The live audience, The Wyatts and The Sheild, were all fairly baffled by the situation, and security quickly dragged him away. He would later serve 10 days in jail for criminal trespassing.
#6: Stripping at WrestleMania
It's pretty much the dream of every wrestling fan, and every wrestler, to reach the main event of WrestleMania. The match is the pinnacle of the industry, and as a result of that, you'd expect there to have been plenty of attempted ring invasions over the years.
Surprisingly, there have been very few, with the one notable exception being at WrestleMania 23, just before the start of the Shawn Michaels Vs John Cena main event.
A fan ran into the ring and took off his shirt, only to be quickly taken out by security. Michaels, ever the professional, just sat and laughed at the invader, waving him goodbye as he was being taken out of the arena.
#5: Triple H saves the day
Mothers-in-law can be notoriously difficult to win over, but if one thing is sure to work, it's saving her from an attack on live television.
Despite being against her in the storyline, Triple H took down a fan who had jumped the barricade to attack his future Mother in Law on an episode of Raw in 2000. The incident was caught live on TV, with JR and Jerry 'The King' Lawler both just expressing shock at what they were witnessing in-front of them.
Being the professionals that they are, McMahon stood and stared as it went down, keeping her icy demeanour intact, while Triple H quickly returned to character just moments after the brief encounter.
#4: Eddie Guerrero takes out an invader
As we've seen on this list, there are several different ways fans can get into the ring, but by far the stupidest thing to do is to actually try and attack a wrestler. Not only are you going to secure yourself a nice bit of time behind bars, but there is also the risk of legitimately injuring one of the performers.
One of the worst examples of such idiocy was when a fan interrupted a ladder match between Eddie Guerrero and Rob Van Dam and tipped the ladder while Guerrero was on it.
Thankfully, Guerrero managed to react quick enough and land on his feet. He then promptly landed a right hook on the intruder before he was dragged off by security.
#3: A British Invasion
If there's one thing you can rely on a British crowd for, it's a rowdy atmosphere. Her Majesty's loyal servants have a bit of a reputation for having a drink or two, and presumably, that was what inspired three men to jump into the ring at a SmackDown taping in London.
Just before the night's main event, which was a four-man tag-team match pitting the team of Daniel Bryan and John Cena against Cesaro and Tyson Kidd, the three men entered the ring and thought it would be a good idea to hit some wrestling moves on one another.
One of the fans hit a Rock Bottom on another one and proceeded to celebrate, while the wrestler's looked on in disbelief.
Security promptly arrived and removed the three men, and because the whole thing was being pre-taped, we will never know how good that Rock Bottom was either.
#2: Chris Jericho helps two fans get engaged
Not so much of an invasion, but more of an invitation. Back in 2014, during a tour of Australia, Chris Jericho helped a friend of his, Daniel House, propose to his girlfriend in front of the WWE Universe.
The event took place at a house show in Melbourne, in front of a live audience of over 13,000 people. Jericho got the two in the ring, and thankfully, she said yes and the whole crowd celebrated along with the duo.
While wrestlers can often get a hard time in the press, it's time like this that goes to show the special bond the performers share with the WWE Universe.
#1: The Yes! Movement invades Raw
Back in 2014, Daniel Bryan could do no wrong. In the eyes of most wrestling fans, he was a god among mere mortals and his popularity was being compared to that of Stone Cold Steve Austin.
Just a few weeks before he would face Triple H at WrestleMania 30, Bryan stood in the middle of the ring, cut a promo, and then proceeded to welcome fans into the ring, the majority of which were wearing white 'YES!' t-shirts.
The image of Bryan stood atop his people is one of the most iconic WWE moments in recent memory, and is easily the most memorable, and welcomed, fan invasion in the history of the WWE.