Lord Tirek

Lord Tirek is a centaur and the main antagonist of the season four finale episodes. He is a villain who escapes from Tartarus and steals magic.

Development and design
Tirek shares his name and certain aspects of his design with a Generation 1 villain from the animated television special Rescue at Midnight Castle. He is a centaur with reddish skin, a white beard, and black fur, and is somewhat bovine in appearance. As the episodes progress, his appearance gradually changes from a frail, pony-sized stature to a tall and robust one, with increasingly pronounced and curved horns.

During her May 2014 takeover of the Hub Network's Twitter feed, Meghan McCarthy identified Tirek as her "new favorite character", and described Tirek as having "some serious issues and some serious magic". On May 10, 2014, Jayson Thiessen tweeted "hehe" in reply to a fan's tweet "Was just rewatching episodes with a friend. Was that Tirek at the end of Castle Mane-ia? My mind may have just blown."

Depiction in the series
Tirek appears for most of Twilight's Kingdom - Part 1 in a frail, weakened state. In a Canterlot alleyway,  he approaches the unsuspecting unicorn Rare Find and drains his magic, growing larger and more powerful. This attack is sensed by Princess Celestia in a vision, causing Princess Luna to see it and become aware as well.

In a scene similar to the opening scene of the first episode, Celestia and Luna narrate that Tirek and his brother, Scorpan, came to Equestria from "a distant land" to steal Equestrian magic. However, Scorpan grew to appreciate the ways of Equestria and even befriended a young unicorn wizard. Scorpan pleaded with his brother to abandon their plans, but Tirek refused to relent. To save Equestria, Scorpan informed the Princesses of Tirek's intentions, leading to Tirek being imprisoned in Tartarus for his crimes while Scorpan returned to their own land.

Celestia states that Tirek likely escaped during the events shown in It's About Time, when Cerberus left his post at Tartarus' gates, and has only recently regained enough strength to use his dark magic after languishing in Tartarus for centuries.

While continuing to devour unicorn magic, Tirek is captured by Discord on behalf of his friendship to the ponies. Likening Discord's actions to those of his "weak-minded brother", Tirek appeals to Discord's former nature as a master of chaos, convincing him that friendship is "a new form of imprisonment", and that betraying the ponies will grant him freedom to do what he pleases. With Discord's aid, Tirek absorbs enough unicorn magic to be able steal the magic of Pegasi and Earth ponies as well.

In Twilight's Kingdom - Part 2, Tirek becomes powerful enough to steal Alicorn magic, and arrives in Canterlot. Anticipating this, Celestia, Luna, and Cadance transfer all of their magic into Twilight Sparkle and send her into hiding, believing Tirek is unaware of her existence as a fourth princess. Discovering the princesses' plan, Tirek banishes them to Tartarus, and gives Discord a medallion originally belonging to "someone very close" to him as a token of gratitude and loyalty. He then discovers Twilight via her depiction in a stained glass window, and is directed by Discord to her home in Ponyville.

After the two arrive and capture Twilight's friends, Tirek absorbs their magic and grows even more powerful. Discord is thrilled by the prospect of ruling Equestria alongside Tirek, but Tirek says Discord is no longer of use to him and absorbs his magic as well; when reminded of the medallion he gave Discord, Tirek says the medallion was given to him by his brother Scorpan, and considers it to be "as worthless as he is".

Tirek finds Twilight, who battles him in an explosive and destructive duel using the magic bestowed on her by the princesses. Noting their powers are evenly matched, Tirek offers Twilight a trade: the release of her friends in exchange for the Alicorn magic. Despite her friends' protests, Twilight agrees to trade the magic for her friends, including Discord. After releasing them, Tirek promptly absorbs all of Twilight's magic, making him all-powerful.

However, Twilight and her friends discover Tirek's medallion is the final key to open the Tree of Harmony chest, and do so before Tirek discovers and attempts to stop them. The chest bestows the ponies with a new, powerful magic that Tirek is unable to overpower. With this magic, the ponies reduce Tirek to his weakened state once more. He is last seen locked in a cage within Tartarus, guarded by Cerberus.

Personality
Tirek displays evil and narcissistic tendencies, his most obvious one being his obsessive desire for power. He can also be very manipulative and is shown to possess a talent in making great sense and persuasive points when trying to strike a deal.

However, he has little regard for following his end of a bargain, and is bitter and traitorous, not hesitating to turn on and dispose of anyone whose usefullness has expired, like Discord.

He harbors a deep resentment toward his brother Scorpan after his betrayal, describing him as "weak-minded" and "worthless".

Powers and abilities
Tirek is one of the most potentially powerful magic users in the show, as evidenced by his magical battle with an empowered Twilight Sparkle. Once freed from Tartarus, however, his magic is severely drained, forcing him to leech off of unicorns' magic and grow stronger. With Discord's help in rounding up the other pony types, he is able to absorb the power of Earth ponies and Pegasi as well.

Once he absorbs the magic of the Twilight's friends and Discord, Tirek gains enough power to be able to stand up against Twilight Sparkle, who at the time is empowered by both her own innate Alicorn magic and that of her fellow princesses. His subsequent deal with Twilight shows that he can also control Discord's powers of chaos, demonstrated when he snaps his fingers and brings Twilight's drained friends and Discord to her in soap bubbles. After he absorbs Twilight's Alicorn magic as well, Tirek grows from his already-impressive magnitude to a size comparable to that of a hydra.

Tirek's magical prowess after absorbing the magic of nearly every pony in Equestria puts him on equal standing with a magically empowered Twilight. He shrugs off a blast of Alicorn magic by simply crossing his arms and creating an energy shield; then he telekinetically slams her into a mountain and rams her through said mountain with his horns. Tirek's own magic beams manifest from a glowing orange orb that forms between his horns, sparkling with black electricity.

Quotes
"'Is he friend, or is he foe?' the pony wonders. I can assure you... I am no friend. I am Lord Tirek, and I will take what should have been mine long ago."

- Twilight's Kingdom - Part 1

"Oh, please, I've seen this before. But he was always weak minded. You are Discord, you are legend, you cannot fall into the same trap that claimed my brother! Help me to grow strong, and be rewarded with something far greater than friendship: freedom."

- Twilight's Kingdom - Part 1

"How does it feel knowing that every Pegasus, unicorn, and Earth pony will bow to my will, and that there is nothing you can do to stop it?!"

- Twilight's Kingdom - Part 2

"Give my regards to Cerberus."

- Twilight's Kingdom - Part 2

"Here, I want you to have something. This was given to me by someone very close to me. I give it to you as a sign of my gratitude and loyalty."

- Twilight's Kingdom - Part 2

"My brother, who betrayed me. It is as worthless to me as he is."

- Twilight's Kingdom - Part 2