Kouichi Nagano is a Japanese voice actor, born on December 12, 1966, in Sakura, Chiba Prefecture. His career in voice acting began after a period of training at the Tokyo Announce Academy, following earlier work at Tokyo Disneyland. He was formerly affiliated with the talent agency 81 Produce before becoming a freelance voice actor.

Nagano is perhaps best known for his long-running role as Helmeppo in the One Piece franchise. He has voiced the character since the series' early episodes, continuing in this role for numerous television installments, original video animations, and feature films such as One Piece: Dream Soccer King!, One Piece: Open Upon the Great Sea! A Father's Huge, HUGE Dream!, One Piece Film: Z, One Piece: Stampede, and One Piece Film: Red. His filmography also includes a range of other characters, such as Ryokan Kurita and Satoshi Muro in Eyeshield 21, Yuichiro Hikari in Rockman EXE, Rai in Beyblade, Romario in Katekyō Hitman Reborn!, and Goz in Hunter x Hunter (2011). Additional roles cited in his career include the Superintendent in The Asylum Session, Ichiro Maeda in Salaryman Kintaro, Hyper DJ in Chosoku Spinner, and Dog and Master Cylinder in Baby Felix.

Throughout his career, Nagano has frequently collaborated with other prominent voice actors, including山口胜平,立木文彦,山口由里子, and冈村明美 across multiple projects. His work extends across numerous television anime series, films, OVAs, and video games, demonstrating his versatility in voicing a wide spectrum of characters. His long-standing association with the One Piece series and his contributions to many other classic and contemporary anime constitute his major professional achievements.