Katsuki Bakugo (Japanese: 爆豪 勝己, Hepburn: Bakugō Katsuki), also known by his nickname Kacchan (used by Izuku Midoriya in the series) (かっちゃん, Kacchan) and his hero name Great Explosion Murder God Dynamight (大・爆・殺・神ダイナマイト, Daibaku Kisshin Dainamaito), is a superhero and one of the main protagonists of the manga series My Hero Academia, created by Kōhei Horikoshi. Katsuki's Quirk is Explosion (爆破), which allows him to make explosions from his hands by detonating the nitroglycerin-like substance he sweats; throughout the series, he learns various different ways to apply this. Overuse of the Quirk can cause pulsating pain in his arms and shoulders.

As a child, Katsuki bullied his childhood best friend, the Quirkless Izuku Midoriya giving him the moniker Deku. However, after they both entered U.A. High School and Katsuki lost to Izuku in training, he began to see him differently. After Katsuki is kidnapped by the League of Villains, All Might loses his Quirk in the process of saving him, which made him blame himself for All Might's retirement, though All Might later reassures him it was not his fault. Katsuki later becomes one of the only people who knows the true nature of Izuku's Quirk as Izuku trusts him with this secret and so did All Might.

Katsuki is voiced by Nobuhiko Okamoto in Japanese and Clifford Chapin in English. His character has received positive reviews from critics, with many praising his development throughout the series and his relationship with Izuku. The voice performances in both Japanese and English dub also received praise. The character has also consistently ranked in the series' popularity polls, most commonly he placed first. Fans have drawn comparison between Bakugo and Vegeta from Dragon Ball franchise.

In the first draft of the series, Katsuki was a genius with a nice personality, though Horikoshi scrapped this idea because it was too boring. Instead, he decided to make the character ruthless and ambitious. Horikoshi originally intended to keep Katsuki with the unempathetic personality, though later decided to give him development into a kinder person as the story went on. After the series' anime adaptation premiered, Horikoshi began writing the character with Nobuhiko Okamoto's voice in mind. Horikoshi had not expected Katsuki to become a popular character, so he was surprised to see the character rank well in the popularity polls.

Katsuki's English voice actor, Clifford Chapin, has commented that he often has to end recording sessions early due to his voice getting worn out from all the screaming the character does. Chapin prefers voice acting the more calmer and emotional scenes with the character, even making the character accidentally sound too vulnerable at times.

Katsuki's Quirk is Explosion; it works by Katsuki sweating a nitroglycerin-like substance from his palms, which he can detonate at will. Throughout the series, Katsuki learns to apply this in different ways, such as to move through the air, create blinding flashes of light, catapult allies towards enemies, or create shockwaves to serve as defense. However, overuse makes his forearms ache.

Katsuki begins the series as an intelligent student with aspirations of being the world's greatest hero, but had an arrogant, violent and crude personality. He often bullied Izuku Midoriya with reasons being currently unknown, during their childhood. Katsuki was the one to give Midoriya the moniker "Deku" (an alternate kun'yomi reading of his given name's kanji that is homophonous with 木偶, meaning "useless person; good for nothing"; treated as a clipped compound of "Defenseless Izuku" in English translations) to mock his perceived worthlessness in superhero society. However, after Izuku was given the generations-old Quirk, One For All, he and Katsuki enter the prestigious U.A. High School and are both enrolled in Class 1-A. Katsuki receives character development on par with Izuku, learning the importance of teamwork and co-operation, becoming a leader, accepting help, and how to save others in order to win. He also begins developing a friendship with classmates Eijiro Kirishima and Denki Kaminari. However, Katsuki still holds onto his habit of yelling.

After being kidnapped by the League of Villains, and refusing their offer to join them, Katsuki is rescued by All Might, his childhood hero. However, All Might's hero career comes to an end as he uses the last of his powers in the fight against the mastermind and his arch-enemy, All For One, which fills Katsuki with guilt that he was the one who put an end to the great hero's career. After failing the Provisional Hero Licensing Exam due to his guilt and aggressive attitude, Katsuki takes Izuku out to Testing Ground Gamma, and reveals he has finally put the pieces together on how Izuku received his Quirk, One For All, from All Might. After that, Katsuki challenges Izuku to a battle to deal with his guilt and ask why it was Izuku who was chosen to receive One For All, when they both grew up admiring All Might just as much as each other. After defeating Izuku, All Might arrives to stop the fight, reassures him that what happened was not his fault, and tells him the Origins of All For One, the injury that limited his hero work, his need for a successor, and All For One. After agreeing to keep this information secret, Katsuki becomes one of the few people to know the truth about One for All. As they return to the U.A. dorms, Katsuki promises Izuku that he will surpass him one day, to which Izuku responds that he will simply have to go even higher still than Katsuki, forming a proper rivalry between the two. Bakugo thinks that Izuku has been hiding his quirk all this time even when Bakugo bullied him for being Quirkless until Izuku explained to him later that he just got it and that it is a borrowed quirk that was passed on to him.