Dr. Daisuke Serizawa

Dr. Daisuke Serizawa was a young colleague of paleontologist Kyohei Yamane, in love with his daughter Emiko, who herself had secretly fallen in love with and planned to marry Hideto Ogata. He saw active combat during World War II, and lost his right eye in battle - his eyepatch was worn to cover the empty socket.

After the war, Dr. Serizawa became a scientist who studied elements and their effects on other objects and organisms. During his studies into the element of oxygen, he discovered a destructive chemical reaction that split oxygen atoms into fluids, forcibly removing all oxygen from a body of water and liquefying any organic material present. He was initially horrified by the destructive potential of his "Oxygen Destroyer" but chose to continue researching it, confident that he could take it beyond its raw form and develop it to benefit society. Meanwhile he kept its existence secret from everyone, even Emiko and Ogata.

Shortly after the first sightings of Godzilla, Dr. Serizawa decided to reveal his secret experiments to Emiko when she visited his home, where she intended to break the news that she planned to marry Ogata. After shocking Emiko with the horrific effects of the Oxygen Destroyer, he swore her to secrecy, explaining that he knew that the world was not ready to know of such a terrible weapon. He remained in his lab during much of Godzilla's subsequent attacks on Tokyo, continuing his research, while Emiko was so shocked by what she saw she couldn't bring herself to tell Serizawa about Ogata.

After Godzilla's second raid on Tokyo, Emiko told Ogata about the Oxygen Destroyer, believing it was the only weapon that could stop Godzilla. She traveled to Serizawa's lab with Ogata, hoping to convince Serizawa to use the Oxygen Destroyer against Godzilla. Serizawa adamantly refused, maintaining that his weapon would only begin a new age of terror once the world saw what it could do. He briefly scuffled with Ogata in defense of his decision, but paused when he saw a report about the devastation Godzilla had brought upon Tokyo. Shaken by the utter destruction, Serizawa finally agreed to use his device, but warned Ogata that he would only use it once.

Unbeknownst to Emiko, Serizawa had every intention to make certain that the secret of his ultimate weapon would remain secret. He burned all of his research, assuring Emiko that this was the only way to prevent his secret from falling into the wrong hands. Serizawa and Ogata traveled with a party of scientists and reporters aboard a boat in Tokyo Bay, locating Godzilla on the seabed with a Geiger counter. Serizawa insisted on accompanying Ogata on the dive to activate his device, saying that he had to ensure it was used properly, since it was the only device he had. Ogata agreed, and the two men dove to the ocean floor, where Godzilla was resting. Serizawa activated the Oxygen Destroyer as Ogata was lifted to the surface. As the Oxygen Destroyer reacted with the surrounding water, Serizawa remarked that his invention had worked, and told Ogata and Emiko to be happy together. He then severed his line to ensure that he, and the knowledge of his terrible invention, would die along with Godzilla.