The character known as Dessler is the supreme leader of the Gamilas Empire, a race of blue-skinned humanoids. He is a complex figure who evolves significantly over the course of his appearance in the original Space Battleship Yamato series and its sequels. Physically, Dessler resembles a man in his early thirties, with golden hair and black eyes, and is always seen wearing a grey officer's suit complemented by a red-on-black cape and white gloves.

His personality is a blend of contrasting traits, making him a memorable and layered antagonist. On the surface, Dessler is charming, flamboyant, and cultured, possessing a sharp intellect and a flair for the dramatic. He is also an exceptionally skilled military tactician. However, these qualities are paired with a deep-seated arrogance, a nihilistic worldview, and a very low tolerance for failure among his subordinates, often rewarding incompetence with severe punishment. In the initial series, he appears as a ruthless dictator driven by a superiority complex, but it is gradually revealed that his aggressive expansion, including the radioactive bombardment of Earth, was born not from simple malice but from grim necessity. His own homeworld of Gamilas was becoming unstable and faced imminent destruction, compelling him to secure a new, habitable planet for his people's survival.

Dessler's role in the story is primarily as the central antagonist throughout the Yamato's maiden voyage to Iscandar. He deploys his vast fleet and devises numerous elaborate traps to destroy the Earth vessel, all of which the ship and its crew narrowly escape. Despite his constant failures, he develops a grudging admiration for the Yamato's resilience and the tenacity of its crew. His motivations shift after his apparent defeat. He is rescued by the White Comet Empire but becomes consumed by his rage and desire for revenge against the Yamato. This vendetta reaches its peak in a final, personal confrontation with the ship's crew. During this battle, he witnesses the devotion between two of the Yamato's officers, Susumu Kodai and Yuki Mori. This moment triggers a profound change of heart; Dessler renounces his quarrel with Earth, provides critical information for defeating the Comet Empire, and withdraws, effectively ending his role as a direct threat.

Key relationships are central to his development. His animosity towards the Yamato, specifically the officer Susumu Kodai, is the primary driver of his actions for much of the story. This hatred eventually transforms into a deep respect and an unlikely friendship. Another significant influence is Queen Starsha of Iscandar. Dessler harbors deep, unrequited feelings for her, and her fate and choices continue to affect him long after his change of heart. He is also served by loyal subordinates, most notably Talan, who remains with him through exile and hardship.

Over the course of the subsequent films and series, Dessler's character continues to develop. He is eventually shown leading the surviving remnants of his people in search of a new homeworld. He later liberates the Galman people, the ancestral race of the Gamilas, from the oppressive Bolar Federation. He establishes the Galman-Gamilas Empire and becomes a powerful ally to Earth, demonstrating his complete transformation from a feared dictator to a leader driven by honor, loyalty, and the survival of his people. In these later adventures, his tactical genius is employed in defense of his new empire and in alliance with his former enemies.

Dessler possesses notable abilities, primarily his legendary strategic and tactical acumen. He is a master planner, often designing multi-layered schemes that exploit the psychology of his opponents. His personal combat prowess is demonstrated on several occasions, but his most famous ability is tied to his flagship, which is armed with the Dessler Gun, a powerful energy weapon of mass destruction that serves as a direct counterpart to the Yamato's Wave Motion Gun.