Credit: The CW

Katherine Pierce (Nina Dobrev) is the character who has made The Vampire Diaries possible. She came to Mystic Falls a century-and-a-half ago, turning the Salvatore brothers into vampires and changing the lives of Damon, Stefan, and all of Mystic Falls forever. With her death potentially coming in the 100th episode, we take a look at just how Katherine is connected to all of our TVDers. This is six degrees of Katherine Pierce!

Damon Salvatore: Damon and Katherine met in 1864. They fell in love — Damon, perhaps, a bit more than Katherine. Katherine turned Damon into a vampire, but then took off into the night in an elaborate escape scheme that had everyone thinking she was entombed in a Mystic Falls crypt. More than 150 years later, Damon returned to Mystic Falls to free Katherine, the woman he still loved, only to discover she had been free the entire time. Now, Damon hates Katherine, as proven by the callous way he fed her to Silas, which should have resulted in her death.

Stefan Salvatore: Stefan was the other point in the 1864 love triangle involving Damon and Katherine. Like his brother, he also fell for the Bulgarian beauty, and agreed to be turned into a vamp to stay with her forever. Katherine claims that she has always loved Stefan and has been spending some of her last days helping him to overcome his PTSD. She has a very, er, intimate approach.

Credit: The CW

Elena Gilbert: Elena and Katherine are enemies with the same face. They are both Petrova doppelgangers, look-alikes of Amara, a thousands-year-old woman who took an Immortality Spell potion and upset the balance of the universe. The doppelgangers are the way the universe rights this unnaturality: by creating doppelgangers who can die. (How’s that going, universe?) Katherine has tried to kill Katherine on numerous occasion, most recently in the Season 4 finale. Elena stuffed The Cure for vampirism down Katherine’s throat, putting her in her current mortal predicament. Ironically, it was Katherine’s desire to kill Elena that forced into motion the path of her own demise.

Klaus Mikaelson: Katherine met Klaus in Middle Ages Europe when she was still human. Klaus recognized Katherine as a Petrova doppelganger and planned to sacrifice her to unbind the werewolf side of himself. When Katherine learned of his plan, she turned herself into a vampire (making her useless as a sacrifice) rather than die in Klaus’s spell. In retaliation, Klaus spent the next 500 years chasing Katherine, vowing to kill the resilient vamp. Now, they are in a seeming truce, as Katherine tipped Klaus off about a plot brewing against him in New Orleans (i.e. the setting of The Originals).

Elijah Mikaelson: Katherine also met Elijah in Middle Ages Europe, and they fell in love. Elijah planned to save Katherine from Klaus’ scheme of sacrifice, but instead Katherine set into motion her own plan: turning vampire and fleeing. Elijah saw this as a betrayal, removing her from his heart — or so he claimed. After some scuffles in Mystic Falls, the two eventually got back together off-screen in Season 4. But it didn’t last very long. Learning of Katherine’s killing of Jeremy Gilbert, he began to doubt if Katherine was capable of love. He left Katherine, despite her pleas to give her a second chance, to hang with his family in New Orleans.

Credit: The CW

Caroline Forbes: Katherine killed Caroline at the beginning of Season 2 as a message to the Salvatores and Elena. Caroline came back as a vampire, of course, and has been awesome ever since. These two haven’t had too much interaction, but recently joined forces at Whitmore College to get more information on the Augustine Society. And it was pretty awesome.

Matt Donovan: Matt has never been a huge Katherine fan. The vamp tried to use him to trigger the werewolf gene in Tyler (i.e. tried to get Tyler to kill Matt). More recently, however, Matt has seemed to thaw to Katherine. He helped Jeremy protect her from Silas and was acting as her personal trainer only last episode. That Matt Donovan is such a softie!

Jeremy Gilbert: Jeremy and Katherine have had a tumultuous past. The worked together in Season 2 to find Mikael, but Katherine has tried to kill Jeremy several times -- once, succeeding (when she fed him to Silas). More recently, these two became tentative allies when Katherine risked her life to save Jeremy from Silas.

Nadia: Nadia is Katherine’s daughter. She was born in 15th century Bulgaria, but was ripped from Katherine’s arms right after. Once Katherine turned vampire, she returned to find Nadia, but could not. She had assumed her daughter was long dead, until Nadia presented herself to Katherine in Season 5. Nadia is both a Traveler (a kind of witch) and a vampire. Though these two don’t get along, they seem to love one another.

Bonnie Bennett: Bonnie and Katherine haven’t interacted as much as other characters on this show. Though Bonnie’s ancestor, Emily, was Katherine’s handmaiden and confidante, Bonnie and Katherine do not seem to like one another.

Did we miss any important Katherine connections? Sound off in the comments below!

Catch the next episode of The Vampire Diaries on Thursday, January 23, 2014 at 8 p.m. ET on the CW, followed by an all-new episode of Reign.

Kayti Burt is a contributing writer for Wetpaint Entertainment with a penchant for all things pop culture. Follow her on Twitter and Google+!