Mark Kovac

Mark Kovac is the main antagonist of the 12th and final season of the FOX series Bones. He is the son of Josep Radik, a foreign General that Seely Booth assassinated prior to the series.

Background
At six years old, Mark watched his father die on his own birthday, but never learned the identity of his killer. After being sent to America by the Red Cross, Mark was adopted and was given the surname Kovac. He later joined the military, where at some point he learned the man who killed his father was a sniper in the U.S military. Kovac swore at that point to make his father's killer [Booth] pay for his suffering, killing everyone he loves before killing Booth himself.

Tracking Down Booth
Kovac abducted Aldo Clemens, an ex-priest who married Booth and Brennan, and tortured him for information about Booth. When he was finished, Aldo Clemens killed himself, but this did not set back Kovac. He deliberately left his body for the FBI to find, leaving balloons behind the murder site, symbolizing how his life was ruined on his birthday. All the Jeffersonian team was able to get was an X-ray of his father's skull before a bomb exploded and destroyed the evidence.

Kovac later murders an old woman to force out a delivery man who formerly served with Booth in the army. Said delivery man had information Kovac wanted; Booth's identity. Now that he had a name and face to match his hated enemy, Kovac sends two hitmen, his father's former bodyguards, to find and kill Booth's two children and father-in-law Max. Max kills the bodyguards protecting the children, but he himself is shot and later dies as a result. Booth eventually tracks Kovac down and arrests him.

Future
Though the series finale has yet to air, it was stated in public descriptions that Kovac will escape prison and once again try to kill Booth, his friends and his family.