In March, Bleacher Report took a look at some of the greatest title reigns in UFC history. There, champions such as Frank Shamrock and Tito Ortiz had their contributions to MMA honored while Georges St-Pierre and Demetrious Johnson were given props for their longevity.

Unfortunately, while some top names dazzle us with their innovative style or amazing staying power, others fail to take hold for one reason or another. Whether it's injuries, contract disputes or misplaced expectations, some title reigns just leave everyone feeling disappointed when they come to an end.

In recent years, Conor McGregor has become a poster boy for this, with two separate championship reigns ending with the promotion stripping him of the belt before ever defending it. That said, he's far from being the only champion to be stripped of the title, and he's even further from being the only one to never successfully defend the strap.

So who else has been stripped? And who else has failed to follow through on the lengthy reigns they seemed destined for? Read on and find out.

Cain Velasquez

Division: Heavyweight
Date: October 23, 2010
No. of Defenses: 0
Length: 385 Days

What Was the Problem?

Cain Velasquez was supposed to be a premier star for the UFC. The Mexican-American was meant to kick down the door to new markets for the promotion, and his dominant win over Brock Lesnar at UFC 121 was supposed to establish him as a mainstream attraction.

Alas, none of that happened.

Velasquez's reign as heavyweight champion was kicked off by the news he had sustained a torn rotator cuff during the bout, which required surgery and a length of time on the shelf. That ultimately translated to more than a full year of downtime, which saw fan enthusiasm and interest in the newly crowned champ steadily decline. 

He returned a year later for a high-profile title defense at UFC on Fox 1 opposite Junior dos Santos, but he wound up on the wrong end of a 69-second knockout.

While there are many similar reigns that lasted roughly 12 months and ended with zero defenses, Velasquez's stands apart because of how big a missed opportunity it was for all involved parties. Though he would ultimately right the ship and reclaim the title in 2012, he never managed to regain that buzz he had after slaying the Beast Incarnate.

Conor McGregor

Division: Featherweight
Date: December 12, 2015
No. of Defenses: 0
Length: 350 Days

What Was the Problem?

McGregor winning the featherweight title was an amazing moment. However, it didn't take long to figure out his time as champion wasn't going to end well.

Just minutes after McGregor smashed Jose Aldo, UFC President Dana White appeared on the Fox Sports 1 post-fight show to discuss his vacating the title. Notorious pushed back against the idea, stating in no uncertain terms he was intent on becoming the UFC's first-ever dual champion and was capable of juggling two belts at the same time.

It's a mystery as to whether the Irishman was being honest, but the UFC gave in to his wishes and booked him to fight for the lightweight belt a month later...and McGregor never looked back.

His lightweight title fight was scrapped and then put on the back burner as he wound up engaged in a bitter feud with Nate Diaz. When that was wrapped up, he faced Eddie Alvarez for the second belt at UFC 205, capturing gold in dramatic fashion. A month later, the UFC stripped McGregor of the featherweight championship in order to set up a dubious interim title bout at UFC 206.

From a business perspective, it was a wise move as McGregor shows no signs of ever returning to 145 pounds at this point. From a PR perspective, though, it sent a bad message.

McGregor taking the featherweight title up to higher weight classes for three consecutive fights and then casting it aside didn't feel like a return to normalcy for the division. Instead, it felt more like a signal that the Jose Aldos, Max Holloways and Chad Mendeses at 145 pounds just weren't worth his time or effort at that point. 

Josh Barnett

Division: Heavyweight
Date: March 22, 2002 
No. of Defenses: 0
Length: 126 Days

What Was the Problem?

When the 24-year-old Josh Barnett destroyed Randy Couture to claim the UFC heavyweight title, it felt like the beginning of something big. The hot youngster had utterly smashed the respected champion and immediately turned his eyes towards the future. 

During the post-fight interview, Barnett called for a cross-sport superfight with the likes of Mike Tyson or Lennox Lewis. If that didn't pan out? Well, he had a loss to heavyweight contender Pedro Rizzo just waiting to be avenged. There was a lot to look forward to from the newly minted heavyweight champion...

Then he was stripped of the title four months later due to a failed drug test and left the promotion. It was a huge blow for the promotion on multiple levels as it saw one of its top stars mauled, cut loose a hot young talent and ultimately empower its rival promotions by giving them a ready-made attraction.

Things ultimately worked out fine for everyone, as Couture found new life in the light heavyweight division, Barnett enjoyed the best years of his career in Japan and the UFC plugged on just fine.

Still, it was a disappointing turn for the then-Babyfaced Assassin, and it's easy to wonder what might have happened with him otherwise.

Dominick Cruz

Division: Bantamweight
Date: December 16, 2010
No. of Defenses: 2
Length: 1,117 Days

What Was the Problem?

From a technical perspective, a case can be made that Dominick Cruz is one of the greatest fighters of all time. Few have been able to blend together wrestling and striking the way he has and for years, he stood as the unsolvable Rubik's Cube of the lower weight classes.

His lengthy 1,117-day reign as UFC bantamweight champion (which was preceded by an 18-month run as WEC champion) seemingly speaks to that excellence, but his three years holding UFC gold were likely the worst of his career.

After exploding out of the gate with title defenses at the expense of old rival Urijah Faber and future flyweight champion Demetrious Johnson, Cruz sustained a serious knee injury on the set of The Ultimate Fighter season 15. An expected one-year layoff following surgery turned to two years due to complications; and just when it seemed he was ready for a title unification bout opposite Renan Barao, a torn groin muscle forced him out of the contest and saw him unceremoniously stripped of the belt.

Though Cruz would eventually reclaim gold in 2016, he is still yet to truly turn the corner health-wise, most recently withdrawing from a UFC 219 bout with Jimmie Rivera due to a broken arm.

Though his career ultimately won't be defined by his injury woes given how successful he has been throughout his 13 years in the business, his prolonged inactivity as champion badly tarnishes what could have been an all-time great reign.

Conor McGregor

Division: Lightweight
Date: November 12, 2016
No. of Defenses: 0
Length: 511 Days

What Was the Problem?

McGregor's reign at 145 pounds fell flat, yes, but it wasn't really that bad on the whole.

Though he never defended the strap, there weren't any particularly interesting contenders around at the time. Max Holloway's heyday hadn't yet arrived, Brian Ortega wasn't even on the top-10 radar, Frankie Edgar was coming off a lopsided loss and Jose Aldo only lasted 13 seconds in his first go-around. Granted, all these would have been interesting fights but it didn't really feel like McGregor had any unfinished business when he left behind the featherweight title.

That's not the case with 155 pounds, though.

When McGregor was first announced to face Rafael dos Anjos at UFC 197, it was met with general excitement among both fans and pundits. Not just because of the pure novelty of that fight, mind you, but because there were so many exciting dream matches awaiting McGregor at 155 pounds.

McGregor vs. Donald Cerrone? McGregor vs. Anthony Pettis? McGregor vs. Tony Ferguson? McGregor vs. Edson Barboza? The possibilities were endless.

Alas, none of these came to pass.

Even in the throes of his rivalry with Nate Diaz, McGregor was open in his commitment to facing Floyd Mayweather in a boxing match and when he won his second belt at UFC 205? That commitment only deepened. 

Unfortunately, while most of McGregor's career to that point had been defined by speed, The Money Fight proved to be a long, drawn-out affair.

Getting the UFC on board with the fight took months of McGregor's time. Getting the UFC, Showtime and the Mayweather camp all on the same page wasn't quick, either. Then, after it was all over, negotiating a new contract with the UFC that accounted for his increased popularity took almost a full year.

For McGregor, the nine-figure windfall he got from the bout likely cures any ills that may have cropped up. Fans and fighters, however, were just left hanging during his 23-month layoff.

He was unceremoniously stripped of the title in April and, ultimately, it's hard not to lament all the possibilities that were missed out on. Yes, he'll return in October for an epic showdown with Khabib Nurmagomedov...but most of the dream matches that had fans drooling back in 2015 have since become impossibilities.

BJ Penn

Division: Welterweight
Date: January 31, 2004
No. of Defenses: 0
Length: 107 Days

What Was the Problem?

This might baffle recent adapters to MMA but, for the first half of its existence, the UFC actually struggled to retain its top talents. 

Many fighters competed outside the Octagon while still under UFC contract. Some, in their competitive prime, left the promotion entirely to compete elsewhere. And on a few occasions, UFC champions took the belt with them to other promotions.

One of the most notorious examples of this came in 2004, with BJ Penn.

At UFC 46, Penn posted one of the greatest upsets in MMA history, defeating long-reigning welterweight champ Matt Hughes via first-round submission. That moment, unfortunately, was immediately followed by news that Penn was leaving the UFC behind to join K-1. 

The UFC's reaction to this? Basically pretend it never happened.

After quickly stripping Penn of the title, the UFC booked Hughes to face hot up-and-comer Georges St-Pierre for the vacant title, a bout which Hughes won in convincing fashion. He followed that up with quick wins over Frank Trigg and Joe Riggs and, from there, dominated Royce Gracie in the biggest fight in UFC history to that point. Those crushing victories and memorable bouts ultimately made it easy to forget that Penn's reign ever happened...which most fans did.

Penn returned to the UFC two years later and was ultiamtely forced back into the lightweight division by back-to-back losses to St-Pierre and Hughes.

He goes down as one of the greatest, most beloved fighters of his era, but his three-month reign as 170-pound champion is never really brought up as part of that.

Matt Serra

Division: Welterweight
Date: April 7, 2007
No. of Defenses: 0
Length: 378 Days

What Was the Problem?

Matt Serra's upset title win over St-Pierre is one of the most memorable moments in MMA history. That's good, too, because if not for that, there wouldn't have been anything to remember his time as champion for.

Initially set to make his first defense opposite former champ Matt Hughes, he coached opposite his rival on The Ultimate Fighter season 6. That fight was nixed due to a back injury sustained by Serra, however, which resulted in the UFC hastily creating an interim title fight between Hughes and St-Pierre at UFC 79. St-Pierre made quick work of Hughes, setting up a blockbuster rematch for when Serra was healthy.

While the creation of the interim title suggested he would be shelved for an extended period of time, the bout was officially announced shortly thereafter for UFC 83, just four months later (and just a year after Serra's initial win).

Serra, quite frankly, had little to offer in the rematch. Despite scoring a quick, brutal over St-Pierre at UFC 69 he quickly wilted under GSP's grappling at UFC 83 and lost via second-round TKO.

That wild fight-over-fight swing ultimately had many feeling like Serra's win was a mere fluke. That's not necessarily true, of course, but it certainly left his reign feeling underwhelming.

Germaine De Randamie

Division: Featherweight
Date: February 11, 2017
No. of Defenses: 0
Length: 117 Days

What Was the Problem?

Nobody really wanted Germaine de Randamie to be part of the featherweight title picture, never even mind winning the belt. 

While there was never any doubt over the Dutch striker's skills, there was little to be particularly enthusiastic about. She was clearly a natural bantamweight so there was no "what if?" fascination about her competing at a heavier weight class.

Worse, at a time when Ronda Rousey and Miesha Tate were still competing, she lacked the star power to hang with the other leading ladies of the UFC. 

As such, many were left scratching their heads when she was chosen to fight Holly Holm for the inaugural UFC women's featherweight champion over the dominant Cris "Cyborg" Justino. Still, a win over the woman to defeat Rousey was sure to endear her to fans and help her break out of the pack, right? 

Wrong.

In an aggressively boring fight, de Randamie managed to narrowly edge out Holm with the help of less-than-active clinch work and a pair of after-the-buzzer punches that the referee inexplicably let slide.

The result left a sour taste in the mouths of many fans, but de Randamie still had the chance for redemption in the form of a call-out of Cyborg. Alas, not only did she immediately pour cold water on the one fight fans were interested in but her team became actively hostile towards Cyborg through the media in the following months, saying they refused to fight her due to a drug test she failed in 2011.

Whether true or not, it was a situation that smelled of cowardice on the part of the Iron Lady and less than four months after initially claiming the title, the UFC unceremoniously stripped her of the belt for refusing to face Cyborg. She hasn't been seen since.