Seo Won-seok is a South Korean voice actor affiliated with Daewon Broadcasting. He joined the company as part of its first voice actor cohort in 2008. His voice is characterized by a deep, sensitive, and nervous tone, which makes him well-suited for calm and composed characters, though he is also capable of humorous or older-sounding roles.

His career encompasses a wide range of work in animation, foreign film dubbing, video games, and special effects dramas. In animation, some of his prominent roles include Frankenstein in Soul Eater, Minister in Yu-Gi-Oh! 5D's, Heath Grice in Black Clover, Macau Cornbolt in Fairy Tail, and various characters in the Korean dub of Adventure Time, where he is noted for voicing over one hundred different minor roles. He has also taken on leading roles in tokusatsu productions, most notably as the voice of Wataru Kurenai in Kamen Rider Kiva.

In addition to his animation and tokusatsu work, Seo Won-seok has lent his voice to numerous video games, including League of Legends, where he voiced four distinct characters, each with unique vocal characteristics. His voice can also be heard in commercials, such as for Lexus, and as the text-to-speech voice for characters in the TWIP service.