Ooki Sugiyama is a Japanese voice actor born on August 5, 1977, in Tokyo, Japan. He was previously affiliated with the talent management firm Production Agumi.

Sugiyama has built a career through numerous supporting roles in anime television series and films since the early 2000s. His filmography demonstrates extensive work across a variety of genres. He is known for playing the character Maroro in the Utawarerumono franchise, providing the voice for the role in Utawarerumono, Utawarerumono: The False Faces, and Utawarerumono: Mask of Truth. Another recurring role is Proto in the Ghost in the Shell: Stand Alone Complex series, including Ghost in the Shell: Stand Alone Complex, its second season 2nd GIG, and the film Solid State Society.

His other notable anime credits include the role of Kum in The Tower of Druaga: The Aegis of Uruk and The Tower of Druaga: the Sword of Uruk, Walter in Project Blue Earth SOS, and Karias Blerster in Noblesse. He also voiced Tetsuya Gōda in Star Driver and its film adaptation, Gulliver in Eureka Seven, Ashura in Naruto Shippuden, and various characters in long-running series such as Case Closed and Gintama. His role in the 2014 anime Tokyo Ghoul is listed as Sōta.

Throughout his career, Sugiyama has frequently worked alongside a number of prominent voice actors. Collaborative records indicate multiple shared projects with actors such as宫野真守, 福山润, 早见沙织, 小清水亚美, 入野自由, and 坂本真绫. Information regarding specific awards or formal recognitions received by Sugiyama is not documented in the available sources.