Seishirō Katō is a Japanese actor who was born on August 4, 2001, in Kanagawa Prefecture. He began his career in entertainment at a very young age, making his debut when he was only 13 months old. While he is primarily known as a live-action film and television actor, his work includes a number of significant voice acting roles in anime and animated films.

Katō's career gained widespread recognition following his breakthrough role in the 2009 NHK Taiga drama Tenchijin. This led to numerous appearances in television dramas, films, and commercials. His filmography demonstrates a range of work from live-action to voice acting.

As a voice actor, he is known for providing the voice for the character Umasou in the 2010 animated film Heart and Yummie (also known as You Are Umasou). In this story about a young Tyrannosaurus who raises a baby Ankylosaurus, Katō voiced the role of the herbivorous dinosaur Umasou. He also voiced a character in the 2019 anime film Hakubo, playing the role of Yuusuke Kijinami.

In addition to original anime productions, Katō has contributed his voice to Japanese dubs of foreign films. Notably, he provided the voice for a young Mumble in the Japanese-language version of the animated film Happy Feet (2006). Another of his dub roles includes voicing the character Max in the Japanese version of Where the Wild Things Are.

A recurring aspect of Katō's career, though not specific to voice acting, is his collaboration with his younger brother, Kenshiro Katō, who is also an actor. The two brothers have appeared together in various projects.

His filmography also includes roles that bridge live-action and animated projects. For example, he portrayed the character Itona Horibe in both the live-action Assassination Classroom films, which were released in 2015 and 2016.