Takahide Ishii is a Japanese voice actor and singer born on June 3, 1993, in Ibaraki Prefecture. He is affiliated with the talent agency WITH LINE and stands 172 cm tall with blood type O. His journey into voice acting was inspired by a live performance he attended of fellow voice actor Mamoru Miyano during high school, an experience that moved him to pursue the profession. Prior to this, he had considered careers in stock trading or as an illustrator. To achieve his goal, he enrolled in the Tokyo Announce Gakuin performing arts college and, in 2013, was a winner at the 7th Seiyu Awards New Voice Actor Discovery Auditions.

Ishii made his professional debut in 2015 with a role in the television anime series Million Doll. He initially belonged to the agency Mouvement before transferring to his current agency, WITH LINE, in 2016. The year 2018 marked a significant turning point in his career when he landed his first major roles, starring as Nanao Wakura in Cute High Earth Defense Club HAPPY KISS! and as Junpei Shirayama in Dimension High School. For Dimension High School, he also performed the opening theme song Here We Go! as part of the unit 4 Dimensions. He continued to secure leading roles in subsequent years, voicing Ryōsuke Minase in the 2022 anime adaptation of the mixed-media project Futsal Boys!!!!!. In 2024, he was cast as Tarō J. Suzuki in Delusional Monthly Magazine and as Tomoatsu Naoe in Plus-Sized Elf. Looking ahead to 2025, he is set to reprise his role as Nanao Wakura in the animated film Cute High Earth Defense Club Eternal Love! and will appear as Tsuyoshi in the anime Chuhai Lips: Canned Flavor of Married Women.

Beyond animation, Ishii has lent his voice to numerous video games, with credits including the popular title A3! and Monster Strike. He has also been a member of the voice actor unit &6allein, which was formed with other talents from his agency. His hobbies and interests include playing fighting games and first-person shooters, as well as baseball and futsal. He has shared that his passion for gaming started at a very young age, even continuing to play with a controller while his arm was in a cast after breaking it at age three. He has also achieved success in local game store tournaments.