Harlock has a design similar to his other counterparts, a lean man with messy brown hair, a scarred face, an eye patch over his right eye that he lost in an accident, and is dressed in generally black clothes which prominently features a jolly roger. His most notable items are a black cloak, his Gravity Saber, and the Bird that perches on his shoulder.
Similar to the original character, Harlock is an individualist with a keen dislike of the corrupt government factions that overlook Earth. He is a very charming individual, able to recruit outcasts that share a passion for living outside of the status quo. The person Harlock speaks to the most is Miime, who provided him the means of his ship. Harlock has full faith that the decisions the crew makes of their own free will can even create a better tomorrow for everyone. Tochiro's death and the mistakes he had made in the past however had caused Harlock to spiral down into a depression that left him bitter and utterly nihilistic. This caused Harlock to want to erase his mistakes and any sense of the Gaia Sanction for making such a horrible circumstance.
When Harlock had seen that the crew and even the Arcadia did not share his wish, he only felt alone and empty as his plan would not come into fruition. Even then, Harlock would stand his ground and see through the barriers that people put around themselves. When Yama found that Earth could support life, Harlock had regained his lost hope. Because of this, Harlock became more open and gave Yama the choice that he once abandoned between hope and despair.
Harlock is an accomplished pilot and leader, having lead an entire squadron of ship in his time in the Gaia Sanction that would only have victories. This did not change as he changed over to the Arcadia, using the ship to its full capabilities to break apart an entire fleet of space battleships. After the dark matter incident, Harlock had become immortal able to live for over a hundred years. His combat skills are also quite impressive, able to fight off groups of enemies single handedly with only his Gravity Saber and Cosmo Dragoon.
Before becoming a pirate, Harlock was once a member of the Gaia Sanction military, rising high in the ranks to become the leader of his own squadron. He was good friends with the engineer Tochiro Oyama and they eventually encountered Miime, a Nibelung who provided the pair with dark matter technology from her home world. Creating a set of four Death Shadow battleships, Harlock was unstoppable. One day however, a dark matter engine went haywire consuming Tochiro in the blast and Harlock losing an eye. The Gaia Sanction kept this incident covered up to save face which lead Harlock to see a glimpse into what the Gaia Sanction truly stands for. The breaking point however came when the Sanction prevented the common folk from visiting Earth near the end of the Come Home Wars.
Harlock stood against the Sanction, using the dark matter of his new ship the Arcadia, Harlock planned to make Earth a place worth living again. Unfortunately, the dark matter had caused the Earth to become barren and caused Harlock to become immortal. Wrecked with guilt and frustration, Harlock would spend the next century gathering a crew and special vibration bombs that he believed would undue his mistake.
Everything seemed to be going right for Harlock, even recruiting the would-be spy Yama and winning him over. But by the time Harlock's plans had surfaced, the crew wanted no part of the plan and Yama had turned on everyone handing Harlock and his crew over to the Sanction. Commander Ezra visits Harlock to inform him of his public execution and to mock how his plans have failed for the better of humanity. Harlock however sees through Ezra's delusional faith in the Sanction, calmly calling out on him. Yet Harlock at this point had truly given up. It was not until Yama appeared with a flower grown on Earth that Harlock regained his composure and broke out of his cell holdings with the rest of the crew to regain the Arcadia.
Back on Earth, the crew manages to broadcast Earth's true state to the entire Sanction watched areas. Harlock had to battle more Sanction soldiers as they boarded the Arcadia, saving Yama from being killed by Ezra. Ezra however boarded the ship to get the Arcadia out of the blast zone of the Jovian Blaster mega weapon. By the second fire, Harlock had the Arcadia shield itself as it crashed down onto Earth's surface. With the final bomb in place, Harlock now has the opportunity to go through with his original plan. But Yama stands his ground with Harlock. Harlock relents giving Yama the detonator for the fate of Earth. Yama decides to abandon Harlock's plan in order for Earth to live on. Satisfied, Harlock hands Yama an eye patch to wear over his right eye that was damaged from the fight with Ezra. Harlock sits on his throne as Yama takes command as the new captain, flying off into space once again.
- In an interview with director Shinji Aramaki, the portrayal of Harlock in the film is meant to evoke the meaning of freedom by taking control of oneself first. This explains Harlock's nihilistic outlook that caused him to give up on everything until Yama arrived and changed everything Harlock had planned on for the better.