Jocasta

 is a powerful witch introduced in the episode A Man Out of Time. She is the great grandmother of Egregor. Although she is over 100 years old, she kept her body young with a spell. She's part of a secret coven that once Emily Bennett was a member of. The coven operates on the very spot that Salem witch trials occurred, and mostly deals with spiritual magic.

Early life
Not much is revealed about Jocasta at this point, except that she is [probably] over 100 years old, since she is the great grandmother of a 22 year old Egregor. She also has heard of Emily Bennett, and is particularly not fond of Bennett witches in general. In time she grew quite powerful, as her knowledge of witchcraft and capacity of magic increased, and she [must have] learned how to channel to the witches that were executed during the Salem witch trials.

Season One
Jocasta's paths crossed with Stefan Salvatore, a vampire considered dead with the rest of his kind, as well as the last known living doppelganger. Stefan sought her coven out in order to ask for a spell that would bring his brother and lover back to life. She and Egregor were willing to help in exchange for a favor in return, which they would ask for in the future. Stefan agreed and she cast the spell. However, without their knowledge, Bonnie had reached out to Damon and Elena and convinced them not to go with Stefan's plan, for if they do, Stefan would have a too big price to pay. As a result, the spell didn't work.

After Stefan was gone, Jocasta found an untouched vial of his blood, which they took from him while his heart was beating in order to use for the spell. As a result, the coven now has access to blood from a living doppelganger. For what they intend to use the blood is yet to be known.

Trivia & Notes

 * , and  were also considered for the role.
 * Character makes a guest appearance in Season One, and doesn't reappear until Season Four where she becomes a recurring cast.