I’ve always thought of him as cruel and ruthless as Azariah kyras from DoW Retribution
 
But the lack of dialog makes i difficult to judge HOW evil he is
 
Kyras was will to sacrifice billions of people to khorne in one blow
 
and the fact Sombra isn’t even some eldritch abomination just a regular unicorn thats gone bad makes him pontetially the worst of all the 4 villains

@CallMeAl  
I like your idea of Shadow Ponies there. They could be like the invading horde from outside the empire. Could Nightmare Moon be a “shadowfied” version of Luna?

@Mayojar77
 
Enh. That wasn’t the most interesting possession plot that I’ve heard. A repentant Sombra wandering the world could go somewhere, though.
 
@ Trickquestion
 
A fan theory contradicts canon if it contradicts something shown on screen. Sombra did stuff besides say “slaves,” even if it wasn’t much.
 
CallMeAl’s version has Sombra turn into a shadow himself, and doesn’t fight with the Royal Sisters. It also made up the shadow ponies out of nowhere, but that technically didn’t contradict anything on screen.
 
@ Background Pony
 
There’s nothing wrong with the song, but entirely too many people have a habit of setting it to repeat while they sit in a dark room and cry about someone unfriending them on Facebook.

@Trickquestion  
Their songs weren’t bad, their fans were just retarded…

@BP  

Crawling in my skin! These wounds will never heal!

@Sjogre
 
The only way a fan theory could contradict canon is if they left out the whole “slaves” and “king” thing. If you think Sombra was an effective antagonist is a matter of opinion, but the fact is we really don’t know anything about him.

@Sjogre  
what about mine?

@CallMeAl
 
That’s actually a pretty interesting story idea, but it isn’t really compatible with what we know of the events.
 
You could try to nudge it into line with canon, or you could go for a full AU. Your choice.

I’ll take a whack at it. Wall’o’text Time!
 
Sombra was a member of a group of settlers sent to colonize the northern wastelands. The settlers happened upon a great source of magic which transformed them. Those among them who valued the beauty of nature became Crystal Ponies, and those who valued industry and progress became Shadow Ponies. As this boon was bestowed upon them, the source of magic erupted, forming crystals. The Shadow Ponies, led by Sombra, saw the potential of the crystals and wished to harvest them, while the Crystal Ponies saw them as an oasis in an otherwise barren tundra and wished to preserve the crystals as-is. Thus became a struggle between the two factions which would decide the fate of the new empire.
 
Sombra himself was strong, ambitious, always striving to extract the greatest results from his resources, whether by motivation or magic. He served as the group’s alchemist, transforming snow and ice into food and water when necessary, and raising sturdy structures from the ground as temporary camps, tearing them down as easily as he raised them. His transformation into a Shadow Pony was very much a curse; though he had the knowledge and magic ability to manipulate the crystals, his Shadow Form corrupted them, draining the very life force of any who touched it, with the exception of other Shadow Ponies. This became a boon, however, as he used the corrupted crystals as seige weapons against the Crystal Ponies to conquer them.
 
Due to their resourcefulness, the Shadow Ponies proved superior and overcame the Crystal Ponies, but the victory was in vain as the Shadow Ponies themselves could not make use of the crystals without corrupting them. Desperate to make use of the crystals, Sombra enslaved the Crystal Ponies to build his empire, with a few left to research a method for purifying corrupted crystals. This proved to be the Shadow Ponies’ downfall, as a strange and incredible power was discovered within the crystals, and the Crystal Ponies used this power to construct the Crystal Heart which purified all shadows within its reach. Most of the Shadow Ponies were slain, with a few left to flee the Crystal Empire. In a final act of desperation, Sombra sealed himself, the Crystal Ponies and the entire Crystal Empire away, hoping that another kingdom would see the wisdom in his efforts and restore him to his seat of power.
 
Sorry if it’s poorly-written, I hadn’t thought much about it, and this is what all I could come up with in about an hour.

@SeraphimDawn
 
Crystal ponies, of course. But ones that had been affected in the same way as the corrupted crystals.

@SeraphimDawn  
Shadow beasts crafted from the souls of the dead mixed with dark-tainted creatures.

Think of him more as Dracula from Castlevania. It would’ve been awesome if they’ve given him minions. You’d think as a king he would’ve had some servants under his influence to further oppress the crystal ponies or “Crrryyssstalll Ssslaaaavesss”.
 
What type of minions do you think he should have?  
Shadow ponies? Black Knight ponies? Crystal Behemoths?

Life can suck when you’re a toothy unicorn with a dark coat living among technologically advanced and colorful (crystal) earth ponies.

Sombra was once a good pony.  
He went on walks, kissed babies, and laid with his now-deceased wife.  
then, an attack on the Crystal empire occurred, and his wife was lost in the process.  
To make sure that never happened again, he opened the book of power, looking for a way to protect his beloved people.  
But the power, it changed him.  
Gone was the loving ruler who would give his life in service of his people.  
Gone was the stallion who would give his mind for peace.  
In his place stood the dark tyrant, Sombra, with a heart as black as pitch.  
Then, a strange beast came to him.  
A disturbed, mismatched and overwhelmingly charismatic creature, bearing a strange proposition.  
This strange creature told him of a series of magical stones, with the power to remove even the most horrible curses.  
In a fleeting moment of lucidity, Sombra asked the beast to tell him more.  
The beast said that these stones could turn the blackest hearts as pure as the virgin snow.  
And all he had to do to be free was become a beast like him.  
So what remained of Sombra’s true mind worked in secret, influencing the encroacher to do horrible things. It made him sick to see these things.  
Once again the beast returned, and told Sombra that his progress was great and that the stones would arrive soon, wielded by two sisters, one a pink so pale it’s almost white and the other a blue so deep that you felt like you could fall into it.  
As he worked they came.  
He was excited.  
Finally he would be free.  
But something was wrong.  
These ponies were fighting with intent to kill.  
He tried to speak: to remind them of their quest, but to no avail, for his mouth was no longer of flesh and blood, and his empire was no more.  
A thousand or more years passed, until he felt his empire again.  
in that time, he gained control of the parasite, enough to control it’s actions, but not it’s words.  
He sensed something faint.  
something familiar.  
Those stones that were supposed to help him before, except different. Kinder.  
Had those sisters seen fit to break his curse?  
To be truthful, even he as not sure.  
As he neared his empire, he could sense his old Phylactery, a crystal heart that was once the last memento of his late wife. He had altered the city so that it fed the phylactery off of the love his people had for him, long before he had become a tyrant.  
Before he realized, he was being thrown away, once again denied freedom.  
But what’s this?  
His body was whole, save for the horn which had broken off, but it had done so many times before.  
It seems, the Phylactery had been purified, allowing him free thought for now.  
Defeated, yet joyful, he set out to find a new place in the world.

I personally think nothing is wrong with Sombra. He may not talk much, but it is the untalkative villains that are dreadful. You usually don’t know what they’re thinking. They tend to be more direct towards their objectives, in Sombra’s case he nearly succeeded. Sombra was quite ingenious with his traps. Shining Armor had his magic jammed, Cadence exhausted her magic, Twilight and her friends were literally helpless. And Spike was only a few seconds away from ending up in his Dragon grave.
 
The only factor that caused him to fail was Shining Armor’s desperate but lucky launch of his “wife missile”.

Here’s my bet, but keep in mind, I am very strange.  

Considering how Sauron-like Sombra was, I’d say his back-story could be similar as well. Perhaps Discord could serve as his Morgoth/Melkor?

Obviously, being turned into a fog monster shattered his mind. He was nothing more than a beast until the crystal heart restored his form. Even then, he was killed before he had a chance to get his bearings.

@Background Pony  
Background: Evil unicorn who took over the Crystal Empire  
Personality: Tyrant who enjoy enslaving ponies
 
Way too little for this fandom.

He has a crystal fetish.

I think that he was kinda like Twilight when he was mortal, a unicorn of exceptional power and intelligence, perhaps as reclusive but not nearly as nice. He studied the crystals of the Crystal Empire, and found a way to modify and control them, by bombarding them with negative emotions instead of positive ones.
 
He planned to use his ability to control the crystals to expand the Crystal Empire over the entire world.
 
Completely unsupported by anything anywhere, but I like to think that he had managed to hatch a dragon that became his only companion. She was Spike’s mother, of course. Her egg and the crystal Celestia used in her demonstration were the only things to survive the downfall of the Empire.
 
Well, maybe one of Cadance’s ancestors.

You guys are all idiots going on about this Sombra crap, he had a personality and backstory, noone pays attention though unless it’s spelled out for you in a monologue like with every other villain we’ve had.

Sombra was Princess Celestia’s personal student one thousand years ago, and was very much like Twilight. However, he never had friends like Spike or the other Elements of Harmony, and eventually crossed the “Lesson Zero” threshold and never came back. He enslaved the entirely Earth Pony Crystal Empire to give himself resources for his continued experiments: Those enslaved ponies were put to work dusting, sorting and resehelving that giant library the Empire had, participating in experiments, or mining the crystals, which he was studying. Celestia could have easily killed him, but couldn’t because she still loved him like a son. He went all One Winged Angel as a result of a forced sealing by Celestia. Time, perspective and finding new love for other students eventually caused Celestia to see killing him as an acceptable outcome, espically considering his new mindless state.