King Sombra (Reflections)

King Sombra (Mirror universe) is a unicorn stallion.

History
Where Equestria's King Sombra was a villainous Umbrum, the Sombra of the Mirror Universe was the exact opposite, a benevolent ruler and heroic defender of his Equestria. In his fight against evil, he was aided by $𝜇$ and $𝜇$. Some time prior to 's encounter with her own world's Sombra, she and Starswirl the Bearded met Sombra after traveling to his world via a Magic Mirror. Despite his standing antagonism with $𝜇$ from his world, Sombra was quickly taken with the young Alicorn princess.

The pair soon fell in love, with Sombra showing Celestia and Starswirl around his world in company with $𝜇$, who at this point was friendly and allied with Sombra. When Starswirl learned that their visits to the Mirror Universe were affecting their own world, he tried to place a limit on such excursions, but Celestia's love for Sombra led her to travel their without his permission. The two made a wish that they could always be together, but after Celestia's return Starswirl sealed the mirror in an effort to prevent Celestia returning. Eventually, Celestia was able to access the mirror again and continue her visits to Sombra's world, but the connection between their two worlds grew dangerously strong as a result.

Matters came to a head after the of Celestia's world was freed from her Corrupted state as Nightmare Moon, which in turn resulted in Sombra's Luna becoming evil and joining her sister. Attacking from the $𝜇$, the pair left Sombra's Equestria in a ruined state despite the efforts of his alliance and noble ponies such as $𝜇$. Eventually, Celestia was attacked by her counterpart during a visit with Sombra, who barely managed to get her back through the mirror to her own world. Seen by her Luna and the Mane Six, he was briefly believed to have been responsible for the attack on her, until Celestia clarified matters.

The evil Celestia and Luna offered Sombra an ultimatum: allow them to take the place of their counterparts in the other Equestria, which would allow him and Celestia to be together and spare his world further suffering. Sombra refused, unwilling to allow another world to suffer under their dominion, and was relieved when the Mane Six arrived on Celestia's instructions. With the Elements of Harmony-something his own world lacked-at their disposal, the six eventually came up with a plan to trap the evil sisters in crystal, so as to halt their evil without doing harm to their own Celestia and Luna. Set on this course, Sombra readied himself for the confrontation by donning armor and placing his and Celestia's written wish inside.

As Sombra and his allies neared the enemy castle, Sombra asked to add a farewell message from him to Celestia to a note  had asked him to write. Confronting the evil Celestia, Sombra again refused her offer, only for her to attack her own Luna in a bid to lure the good Celestia through the mirror. This ended up shattering the mirror linking the two worlds, which began to merge together, and Celestia attacked her evil counterpart while leaving Luna in Sombra's charge. When Twilight and her friends attempted to seal the wicked Celestia in crystal, the effect spread to good Celestia, and Sombra refused to allow them to continue, unable to bear seeing her harmed.

Thinking quickly, Sombra questioned Twilight about her world, and confirmed the news that the Sombra of their Equestria was evil. Taking the Elements of Harmony, he wielded them himself and drew the corruption out of his world's Celestia and Luna, drawing it into himself in order to restore balance between the worlds. Now as dark as his counterpart from Celestia's world, Sombra departed, while the Mane Six, Spike, and the Princesses returned home through the rapidly closing rift. Celestia held on to a piece of the shattered mirror, and through it Sombra was able to hear her parting words to him, shedding a tear as he also said goodbye forever.

Sombra later made his way to an alternate Equestria, where he was among the patrons of Princess Eris' casino.

Appearances

 * Friendship is Magic issue 17
 * Friendship is Magic issue 18
 * Friendship is Magic issue 19
 * Friendship is Magic issue 20
 * My Little Pony (Gameloft) (as costume for Sombra)
 * Nightmare Knights issue 1