Gregory Smith is a supporting character in the Inazuma Eleven series, known for his persistent role as a police detective. He is a middle-aged man, appearing to be in his fifties, with brown hair and a distinctive gray beard. His typical attire consists of a detective's suit and jacket, reflecting his professional identity.

Before becoming a detective, Gregory Smith was a devoted fan of the original Inazuma Eleven team. His life took a decisive turn following the tragic bus accident involving that legendary team, which forced them to forfeit a crucial final match. This event directly motivated him to pursue a career in law enforcement. His primary motivation has always been to uncover the truth behind that accident and to bring those responsible to justice, particularly the mastermind he suspects is behind the corruption in the football world.

In his professional capacity, Gregory Smith is serious, determined, and has zero tolerance for anyone who corrupts or stains the sport of football. He works diligently behind the scenes to investigate anything that threatens the integrity of the game. Despite his grave demeanor when dealing with criminals, he shows a generous and supportive side to young players and good-hearted individuals, often offering them crucial information and assistance.

Throughout the story, Smith plays a key role as an informant and a force for order. He is first seen observing a match where he witnesses a young player perform the legendary technique known as the God Hand, a sight that leaves him speechless given its connection to the past. He later provides that player and his friends with vital information about the original Inazuma Eleven and the suspicious circumstances surrounding their accident. His primary target is the shadowy figure Ray Dark, whom he successfully arrests multiple times for various crimes, including sabotaging matches and creating performance-enhancing drugs. He continues his pursuit in subsequent seasons, investigating disappearances, rescuing individuals from dangerous situations, and traveling to international tournaments to uncover the true objectives of villains like Ray Dark and Zoolan Rice, eventually managing to arrest them as well.

His key relationships are defined by his mission. He maintains a professional and supportive relationship with the main protagonist, Mark Evans, whom he sees as a beacon of pure football. He also shares a connection to the past, as he is a friend of the legendary coach David Evans. His primary antagonistic relationship is with Ray Dark, whose machinations he has been investigating for decades.

As a character, Gregory Smith does not undergo a dramatic personal transformation but instead acts as a constant, reliable pillar of justice. His development is shown in his unwavering persistence, as he follows the trail of corruption from local incidents to international conspiracies, always expanding his investigation and adapting to new threats. He is not a regular player on the field, but in the games, he appears as a recruitable adult character with the goalkeeper position and the fire element. His in-game statistics highlight his physical strength and intelligence, and he can provide the player's team with opportunities for practice matches.