Captain Harlock is a renegade pirate who fights the totalion government controlling dystopian Earth. He is the most infamous criminal in the world he resides in, not only as a physical threat (the Arcadia has a lot of fire power and the crew has won many battles using superior tactics), but also as a charismatic leader who brings others to his cause.
He is an avid believer of existentialism, the philosophy that each individual has the freedom to make their own choices, regardless of what the world would consider right-or-wrong.
He was wildly popular to audiences during the anime space opera scene. His personality (stoic, quiet, sincere, terrifying ruthless badass) was very influential as a character archtype in following media.