Il Palazzo, also written as Ilpalazzo, is the enigmatic leader of the secret ideological organization known as ACROSS, which is dedicated to the goal of world conquest. His name is an Italian word meaning the palace, and it is also the name of a hotel in Tokyo. The character cuts a distinctive figure, typically depicted as a tall man with long, flowing white or pale-colored hair and striking yellow eyes with slit pupils, similar to a cat's. He is often seen wearing ornate armor and a flowing cloak, and he prefers to sit upon a throne within his hideout, underscoring his sense of self-importance and authority.

The core of Il Palazzo's motivation is a deeply held belief that the world has become irredeemably corrupt. His stated mission is to conquer the world, not out of simple greed for power, but to save the ignorant masses from their own corrupted natures. This philosophy is encapsulated in his frequent pronouncement, The world is corrupt, which he often uses as a preface to his orders and speeches. He is the long-time rival of Kabapu, the head of the Fukuoka City Security Department, with their conflict likely stemming from fundamentally opposing views on the state of the world.

A defining aspect of Il Palazzo's character is the sharp contrast between his serious, grandiose ambitions and the mundane reality of his day-to-day existence. While he presents himself as a calculating and suave mastermind, he is often depicted with very little to do while his subordinates, Excel and Hyatt, are out on missions. This leads to the recurring depiction of him pursuing surprisingly ordinary and incongruous hobbies, such as learning to play the guitar, arranging dominoes, or playing dating simulation games. His patience is notably thin when it comes to his overly enthusiastic and incompetent chief officer, Excel. He frequently punishes her failures, often by dropping her through a trap door into a pit, an act he performs with little regard for her well-being.

Il Palazzo maintains key relationships with the few members of his organization. He is the object of Excel's fanatical and obsessive devotion, a one-sided affection he merely tolerates as a necessary annoyance. In contrast, he shows a clear preference for the frail and frequently dying Hyatt, often entrusting her with more complex operations and giving her lighter punishments. This favoritism is evident, making Hyatt his preferred officer. His role in the story is primarily as the orchestrator of ACROSS's schemes, remaining in his headquarters to issue orders and react to the often disastrous results of his agents' missions.

The character's development and portrayal differ significantly between the manga and the anime. In the manga, Il Palazzo is an impenetrable and unflappable figure, perpetually shrouded in mystery. In the anime, however, he is more prone to losing his temper and adopting the quirky hobbies that make him a more comedic figure. Crucially, both versions establish that Il Palazzo suffers from severe psychological disorders. In the manga, this manifests as memory blackouts, hearing voices, and eventually a clear second personality. In the anime, a mental breakdown occurs after he finally succeeds in conquering F City, only to realize he has no plan for what comes next, suggesting he has become a slave to the act of conquest itself.

For most of the story, Il Palazzo does not display any overt superhuman powers, relying instead on his cunning and authority. However, in the climactic episodes of the anime, he demonstrates a sudden and formidable array of abilities. These include great strength, enhanced reflexes capable of catching a missile in mid-air, and telekinesis. It is unclear if these powers are innate to him or are generated by his ornate armor. His distinctive cat-like eyes are a notable physical trait, and it is later revealed that he is a survivor of the ancient lost civilization of Solaria, a background he shares with his rival, Kabapu. This heritage explains his unusual physiology and access to advanced technology.