Seiji Maeda is a Japanese voice actor, singer, and stage actor associated with the agency Hibiki. He was born on July 1, 1993, in Osaka Prefecture. Before pursuing voice acting, he played football in elementary school and tennis in junior high and high school. He was inspired to enter the industry by the anime Neon Genesis Evangelion, citing an interest in experiencing lives different from his own. He studied at the Osaka Visual Arts Academy before moving to Tokyo for further training.

Maeda passed the Hibiki New Voice Actor Discovery Project audition in 2017 and joined the agency the same year. He made his debut in 2018 with roles in anime such as Cardfight!! Vanguard and Future Card Buddyfight Ace. A significant early role was as Shō Yamabuki in the P.A. Works original anime Iroduku: The World in Colors. That same year, he began voicing the Greenhorn Warrior in Goblin Slayer, a role he would reprise in later seasons.

In 2018, Maeda also became a part of Bushiroad's all-male band project, Argonavis from BanG Dream!. Within this multimedia project, he voices the character Wataru Matoba, who is the bassist of the titular band Argonavis. This role involves not only voice acting in the anime and games but also performing live as the bass player for the real-life band, demonstrating his musical talent. He has reprised this role in the television anime, the game Argonavis from BanG Dream! AAside, and the films Gekijōban Argonavis: Ryūsei no Obligato and Gekijō-ban Argonavis Axia. His involvement in the Argonavis project represents a major recurring collaboration with fellow cast members and the production team at Bushiroad.

Another notable recurring collaboration is his long-standing involvement with the Cardfight!! Vanguard franchise. He has voiced multiple characters across several series, including Tatsuya Tachibana in Cardfight!! Vanguard: Shinemon Arc and Samuel Fredson in Cardfight!! Vanguard will+Dress. His work in 2019 also included the role of Tomomi Hōryū in the rugby-themed anime Try Knights.

His career has continued to expand with prominent roles in major productions. He voices Melt Narushima in the popular anime Oshi no Ko. In 2024, he was cast as Wolf Lehman in The Most Notorious "Talker" Runs the World's Greatest Clan and as Gilbert Busch in Let This Grieving Soul Retire!. Beyond anime, his talents extend to stage acting, with performances in productions like ROAD59 -Shin Jidai Ninkyō Tokku-. He is also skilled in sword fighting, a talent he utilizes in his stage roles. Maeda speaks the Kawachi dialect of Japanese and lists his special skills as tennis, sword fighting, and playing video games like Tetris.