|“||When our family first settled here, there was a girl named Tatia, she was an exquisite beauty. Every boy of age desired to be her suitor, even though she'd had a child by another man. And none loved her more than Niklaus.||”|
Tatia was a Petrova doppelgänger. According to both Klaus and Elijah, they both fell in love with her. In order to stop the feud over her, their mother used Tatia's blood to turn them into vampires.
Tatia was a member of the Petrova Family.
During the Middle Ages, Tatia had a child with an unknown man; later in time she met both Elijah and Niklaus, both of whom fell for her. Esther, the mother of Elijah and Niklaus, used her in the spell to create the Original Vampires, with her blood as part of the wine laced with blood Mikael had given his children. Her blood was also part of the spell Esther used to bind Klaus's werewolf side, which resulted in Klaus's werewolf gene being dormant.
The Vampire Diaries
Tatia was mentioned by both Klaus and Elijah during the second season. The first reference of her was presented in the episode Klaus, where Elijah was introduced to Katerina Petrova. Elijah says, "I'm sorry, you remind me of someone." In the same episode, Niklaus tells Elijah about "love" being a vampire's biggest weakness when Elijah tells Klaus about having feelings, caring and humanity. Klaus says that vampires do not feel and they do not care but then Elijah mentions about Tatia by saying "We did once" to which Klaus replies by saying "It`s too many lifetimes ago to matter."
In Bringing Out The Dead, Niklaus and Elijah reveal about their past with Tatia. They both reveal that they loved her and fought for her. Every man desired to be her suitor even though she already had a child by another man. It is also revealed that it was her blood which was laced in the wine they drank before getting killed by Mikael and leading to the creation of The Originals. She doesn't have an modern day appearance.
Silas and other characters make reference to possibly (except Elena Gilbert and Stefan Salvatore) that all doppelgängers have died.
It was indicated by Markos later in the season that Tatia was deceased, because Elena and Stefan were the last remaining doppelgangers living following the death of the last remaining Silas doppelganger.
Tatia is a beautiful young woman with an oval face, almond-shaped brown eyes, and smooth, long dark brown hair. Her height is about 5'6" and she has a slim, slightly athletic physique. Tatia is exactly physically identical to her descendents Katherine Pierce and Elena Gilbert. However, the hair style can change, because Elena and Katherine have different styles.
TVD Season 3
- Bringing Out The Dead (First mentioned by Klaus and Elijah)
TO Season 2
- 2x05 
Tatia is of Russian and Latin Origin, and the meaning is "founder".
- In Bringing Out The Dead, Elijah Mikaelson mentioned that they met Tatia after they moved to the new world. That indicates that she was born in the new world.
- Tatia will make her first appearance on the 27th episode of the Originals. 
- She is the fifth character that Nina Dobrev will be playing in the series.
- She is also the fourth doppleganger that Nina will be playing.
- She was used as part of Klaus's hybrid curse, which Esther had put on him and it was her blood which was used in the creation of The Originals.
- Tatia, like Elena Gilbert, was born in the area of the town that became Mystic Falls.
- They are the only Petrova doppelgangers who were born in Mystic Falls.
- Esther used Tatia's blood to turn her family into vampires. She later used the same method using Elena's blood to turn Alaric into an Original.
- It is most likely she either found peace or was sucked into oblivion when the Other Side collapsed.
- Elijah says Tatia wouldn't choose which brother and that made them estranged so Esther killed her over it.