Tatia, also known as the Original Petrova, was the first known Petrova. Tatia is the progenitor of the Petrova Doppelgänger line which spawned both Katerina Petrova (Katherine Pierce) and Elena Gilbert.
Tatia is/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.
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.
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.
- Bringing Out The Dead (First mentioned by Klaus and Elijah)
Tatia is of Russian and Latin Origin, and the meaning is "founder".
- For a while The Original Petrova's name was thought to be Charlotte, but it was just a name mentioned by Julie Plec in an interview with Entertainment Weekly.  The character's appearance in the series is not confirmed yet.
- In Bringing Out The Dead, Elijah mentioned that they met Tatia after they moved to the new world. That indicates that she was born in the new world.
- She will be the third character that Nina Dobrev will be playing, if she does appear in the series.
- She was used as part of Klaus's hybrid curse, which Esther had put on him.
- It was her blood which was used in the creation of The Originals.
- Tatia, like her doppelgänger Katherine, is said to have had a child out of wedlock.
- Tatia, like her doppelganger Elena Gilbert, was born in the area of the town that became Mystic Falls.
- Julie Plec stated in an interview that they have no intention of exploring The Original Petrova's story anytime soon.
- 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.