Karl Martin is a young Other. He is played by Blake Bashoff, and has appeared in nine episodes to date.
Karl appears to be at odds with the Others, as he was first seen residing in a cage and sought to escape to the Oceanic survivors' camp. He has a girlfriend, Alexandra Rousseau.
Before Oceanic 815
Karl was kept alone in one of The Hydra's cages until James "Sawyer" Ford was deposited in the nearby polar cage. He tried to get information from Sawyer about how far his camp was and what the survivors were like, but found Sawyer less than receptive to his questions. Picking the lock to his cage, Karl freed Sawyer and told him to run. But the two were shortly recaptured and Karl was forced by Tom to apologize to Sawyer before being taken away. His girlfriend, Alex, tried to locate him afterwards, but her best chance came when Sawyer and Kate escaped. The group found Karl inside Room 23, strapped to a chair with an IV inserted into his arm, loud music playing, and forced to watch a video montage. Karl, semi-conscious, was freed from this brainwashing and carried by Sawyer to Alex's outrigger canoe and escaped from The Hydra with Sawyer and Kate.
Upon making it to the main island, Karl told Sawyer and Kate about how the Others lived on the main island - at the barracks - and that The Hydra was only a place they went to work on projects. On the subject of the kidnapped tail section survivors, he only told them that those survivors were given a better life than the ones the mid-section survivors have been living. Sawyer later had a private talk with him about Alex and, afterwards, let him go to rescue her.
Karl eventually made it back to Alex, but the Oceanic survivors discovered the barracks and Ben Linus ordered the Others to abandon the facility and move to the temple. As Karl was still at ends with Ben, he was forced to follow the Others at the distance as they traveled across the island. Alex eventually discovered her father's plans to send Ryan Pryce and a strike team to the Oceanic survivors' camp to kidnap their pregnant women. She sent Karl to the survivors' beach camp to warn them of the impending assault. Making it to their camp, Karl was vouched for by Sawyer and was able to warn them in time. He accompanied the survivors on their journey to The DHARMA Initiative's radio transmitter in order to turn off Danielle Rousseau's distress signal so Naomi Dorrit's satellite phone could be used once Charlie and Desmond deactivated The Looking Glass' jamming equipment. On the way there, Ben intercepted the survivors with Alex in an attempt to persuade Jack from contacting Naomi's off-island freighter. Ben failed, and Karl and Alex were reunited and learned that Danielle was Alex's mother.
The Oceanic survivors eventually learned of Charlie's death and warning regarding Naomi Dorrit and her supposed rescue freighter. The survivors split into two groups: those who believed in Charlie sided with John Locke while those who still believed in rescue sided with Jack Shephard. Alex chose to go with Locke and Karl went with her. Ben and Danielle were among those who sided with Locke. Locke's group left for the barracks and Locke believed it was the only safe place on the island.
On the way to the barracks, the group met one of the people from the freighter, Charlotte Lewis. Ben eventually revealed he had detailed information about her and her compatriots as they were on the island for him. Charlotte was taken prisoner and brought with them. At the barracks, the group waited as Locke tried to figure out their next move. Sayid Jarrah came to the barracks for Charlotte and exchanged her for another person from the freighter, Miles Straume. Locke interrogated the man and shared his findings with the group. The people on the freighter did indeed come for Ben and were going to kill everyone else on the island once they had him. Ben believed the men on the freighter would use his daughter against him, so he asked her to go to the Temple, a place of sanctuary and safety where the rest of the Others were. Alex agreed and Karl accompanied her and Rousseau. As they journeyed to the Temple, Karl expressed his doubts as he believed Ben may have been lying to them. However, the group were fired at with silenced submachine guns and Karl was struck in the chest and killed.
- 3x01 - A Tale of Two Cities
- 3x07 - Not in Portland
- 3x09 - Stranger in a Strange Land
- 3x21 - Greatest Hits
- 3x22 - Through the Looking Glass (1)
- 3x23 - Through the Looking Glass (2)
- 4x01 - The Beginning of the End
- 4x02 - Confirmed Dead
- 4x08 - Meet Kevin Johnson
- 3x01 - A Tale of Two Cities: Tries to escape, freeing Sawyer, but the two are caught shortly after.
- 3x07 - Not in Portland: Is freed from Room 23 and escapes the Hydra island, but without Alex.
- 3x09 - Stranger in a Strange Land: Is freed by Sawyer to go after Alex.
- 3x21 - Greatest Hits: Warns the Oceanic survivors that the Others are planning an attack.
- 3x23 - Through the Looking Glass (2): Travels to the radio tower with the Oceanic survivors.
- 4x01 - The Beginning of the End: Goes to Locke's group with alex and Danielle after the survivors split in two.
- 4x02 - Confirmed Dead: Travels to the barracks with the rest of Locke's group.
- 4x08 - Meet Kevin Johnson: Is shot and killed by Keamy and the rest of the freighter's security team.
Although his last name hasn't been mentioned on the show, it was revealed by the producers during Comi-Con 2009.