Booker Kudo, known in the original Japanese as Yusaku Kudo, is the father of high school detective Shinichi Kudo and husband of former actress Yukiko Kudo. He is a world-renowned mystery novelist, celebrated internationally for his popular Night Baron book series. His sharp intellect and masterful understanding of the criminal mind, honed through his writing, have made him an exceptional detective in his own right, often surpassing the abilities of his son.

In his younger years, Kudo was already known for his keen deductive skills and assisted Inspector Megure of the Tokyo Metropolitan Police with difficult cases, becoming a good friend and valuable advisor to the inspector. While he supported the police, his primary aspiration was always to be a writer. He met his future wife, Yukiko Fujimine, a famous and beautiful actress, when one of his novels was adapted for a film in which she starred. He famously proposed to her immediately after brilliantly solving a murder case during a dinner at a high-end restaurant. The couple eventually moved to Los Angeles, leaving their teenage son in Japan, but they maintain strong ties to their home country and return frequently.

Personality-wise, Booker Kudo is remarkably laid-back, calm, and rarely seen losing his temper. This relaxed demeanor can sometimes be misinterpreted as being too casual, such as when he took a young Shinichi to crime scenes or showed little concern over his six-year-old son leading friends into potentially dangerous situations. Despite his success, he can be somewhat cocky and has a noted lack of talent for making humor. He is also known to occasionally blow off his editors to travel with his wife, which is one of the few things that can truly fluster him. His love for reading is immense, and he is responsible for compiling the vast library of mystery fiction that shaped Shinichi's childhood.

Booker Kudo's role in the story becomes critical after he learns from neighbor Professor Agasa that his son has been poisoned and transformed into the child Conan Edogawa. Understanding the lethal danger posed by the Black Organization, he stages an elaborate false kidnapping, disguising himself as the Night Baron to demonstrate the stakes and test Shinichi's resolve. He offers to take Conan to a new life in America where he could use his contacts to research the organization and search for an antidote. However, when Shinichi refuses, wanting to stay near his childhood friend Ran Mouri and pursue the case independently, Booker respects his son's decision, even though he privately doubts the resolve will last. From that point, he and Yukiko serve as occasional but powerful allies, checking in on Conan and providing crucial assistance from afar or during their returns to Japan.

His key relationships are central to his character. His marriage to Yukiko is loving, though marked by frequent, good-natured arguments that typically end with Booker apologizing. His relationship with his son is one of deep respect and intellectual kinship; he understands Shinichi's feelings for Ran and acknowledges the maturity of his decision to stay, even if he disagrees. He shares a long-standing friendship with Professor Agasa, who keeps him informed on Conan's activities, and with Inspector Megure, who still values his insights. In a significant and later-developed connection, it is revealed that Booker has a long history with the original Kaitou Kid, implied to have known his true identity and engaged in a sort of competitive friendship with him. This connection deepens further when it is disclosed that the first Kaitou Kid, Toichi Kuroba, is actually his long-separated twin brother, making the second Kaitou Kid, Kaito Kuroba, his nephew.

Throughout the series, Booker Kudo demonstrates notable personal development. While initially content to observe from a distance, he becomes more directly involved as the threat of the Black Organization grows. He has provided critical support by using his acting skills to disguise himself as another character to help Conan maintain a vital secret. He has also used his unparalleled deductive reasoning to make a monumental breakthrough in the case, successfully deducing the identity of the Black Organization's elusive leader after analyzing key pieces of information. His decision to eventually return to Japan permanently with Yukiko signifies a shift from a passive advisor to an active participant in the final confrontation.

His most notable ability is his world-class intellect. He is consistently portrayed as being a step ahead of his son, capable of solving complex cases faster and with far fewer clues. This is complemented by a deep and advanced knowledge across numerous subjects. While not a primary skill, he also possesses capable acting abilities, having effectively performed in complex disguises to deceive even highly perceptive individuals.