Kol Mikaelson

Kol Mikaelson is a villain in the Vampire Diaries series appearing in the third and fourth season. He is one of the Original Vampires and is the son of Mikael and Esther, the younger brother of Elijah and Finn Mikaelson, the older brother of Rebekah Mikaelson and the younger half-brother of Klaus Mikaelson. He was killed by Jeremy and Elena Gilbert to complete the Hunter's Mark on Jeremy. He temporarily came back to the land of the living when Bonnie lowered the veil to the Other Side. Seeking revenge, he hunts down Elena as she assisted in his death, and attacks her, but is sent back to the Other Side when Bonnie  puts the veil back up. His ghost was later seen on the Other Side, appearing to Matt after he temporarily died. He tells Matt the Other Side is being destroyed after Markos broke free. After Vicki is pulled into oblivion, Kol begs Matt to find a way to stop the Other Sides destruction, fearing what happened to Vicki will happen to him and all the other ghosts.