|“||If any harm comes to my son because of what you did, you will answer to me.||”|
Dr. Jonas Martin was an extremely powerful warlock and also the father of Greta and Luka Martin. He teamed up with a powerful vampire named Elijah, in attempt to kill Klaus after he kidnapped his daughter. While trying to help Elijah, his son is killed by Damon Salvatore, which led Jonas to go on a rampage and hurting many people before him finally being killed by Stefan Salvatore.
Jonas was a member of the Martin Family.
Dr. Martin is first seen at the Mystic Grill with his son, Luka. He introduces himself to Bonnie, who is also a warlock. Jonas begins asking Bonnie questions about her family, and if they originated from Salem, Massachusetts. Bonnie becomes suspicious of the Martins, and soon discovers they are male witches. Untrusting of the Martin Warlocks, Bonnie bewitches Luka and forces him to tell her why they are working with vampires. Bonnie then discovers that Jonas' daughter, Greta, was kidnapped by Elijah’s brother, Klaus, who has been forcing generations of witches into breaking his curse, without the use of a doppelgänger. Jonas becomes enraged and strips Bonnie of her powers as a punishment.
In The House Guest, Jonas discovers that Elijah was killed by the Salvatore’s, and sends Luka to revive him. Later that night, Dr. Martin enchants a spell that sends Luka in an astral projection form to resurrect Elijah, but is sadly killed by Damon Salvatore during the mission. Full of anger and grief, Jonas plots a vendetta against Elena and attacks her in the grill injuring many people including Matt Donovan but Elena escapes.
After the grill he went to the Gilbert's House and tried to kill her again in the bathroom but this time it was actually Katherine who bite him and presumably killed him. However, Jonas manages to survive and leap up after his attack, grabbing Bonnie so Stefan Salvatore rushes over and breaks his neck. It is later revealed, when Jonas grabbed Bonnie, he was only returning her powers and telling her how to kill Klaus.