Kōichi Yamadera (山寺 宏一code: ja is deprecated , Yamadera Kōichi, lahir 17 Juni 1961) adalah seorang pengisi suara, pemeran, tarento, dan pembawa acara Jepang.^[1][2] Ia lulusan Jurusan Ekonomi Universitas Tohoku Gakuin, dan berada di bawah manajemen artis Across Entertainment (sebelumnya di Tokyo Actor's Consumer's Cooperative Society.^[1] Pada tahun 2012, ia menikah dengan pengisi suara bernama Rie Tanaka (sebelumnya dengan pengisi suara bernama Mika Kanai, 1993-2006).^[3][4] Ia juga mengisi suara Donal Bebek versi bahasa Jepang dalam permainan Kingdom Hearts dan Kingdom Hearts II. Yamadera juga merupakan pengisi suara dalam dubbing Jepang Will Smith dan Jim Carrey.

• Oh My Goddess! (Troubador)
• Soreike! Anpanman (Cheese, Kamameshidon)
• Agatha Christie's Great Detectives Poirot and Marple (Gale)
• Cowboy Bebop (Spike Spiegel, Ein)
• Kyattou Ninden Teyandee (Karamaru)
• Galaxy Angel (Colonel Hari)
• Ghost in the Shell: Stand Alone Complex (Togusa, Aoi, Baby Ruth)
• Ghost in the Shell: S.A.C. 2nd GIG (Togusa)
• Samurai Champloo (Sakonshougen Nagamitsu)
• Neon Genesis Evangelion (Ryoji Kaji)
• Fist of the Blue Sky (Kenshirō Kasumi)
• Special Duty Combat Unit Shinesman (Shogo Yamadera / Shinesman Gray)
• Xenosaga (Gaignun Kukai, Albedo Piazzola)
• UFO Baby (Yuzupiko)
• Dokkiri Doctor (Doctor Haruka Nishikikōji)
• Dragon Ball Z (Tenshinhan, pengganti bagi Hirotaka Suzuoki)
• Donkey Kong Country (Donkey Kong)
• Bakumatsu Kikansetsu Irohanihoheto (Sakamoto Ryōma)
• Honey and Clover (Lohmeyer-senpai)
• Peter Pan no Bōken (Cecco, Nana)
• Pokémon (Farfetch'd)
• Brave Exkaiser (Tokuda Osamu)
• Ranma ½ (Jusenkyo Guide, Ryoga Hibiki)
• Lilo & Stitch: The Series (Stitch)
• Memories of the Flame: Tokyo Crisis (Michael Suzuki)
• Operation: Return the Treasure (Iwan Kurokobich)
• Mermaid Saga (Yuta)
• Kaiketsu Zorori (Zorori)

• The Return of Jafar (Genie)
• Aladdin and the King of Thieves (Genie)
• Legend of the Galactic Heroes (Bruno von Silverberg)
• Ghost in the Shell: S.A.C. Solid State Society (Togusa)
• The Hakkenden (Inuyama Dōsetsu Tadatomo)
• Detonator Orgun (Tomoru Shindo, Orgun)
• Photon (Papacharino Nanadan)
• Megazone 23 (Shinji Nakagawa, Shion)
• The Lion King 1½ (Donald Duck, Genie, Stitch)
• The Little Mermaid II: Return to the Sea (Sebastian)
• Mermaid Forest (Yuta)
• Cinderella II: Dreams Come True (Jaq)

• Ice Age (Manny)
• Ice Age 2: The Meltdown (Manny)
• Arashi no Yoru Ni (Barry)
• Aladdin (Genie)
• Cowboy Bebop: The Movie (Spike Spiegel)
• The Prince of Darkness (The North Star)
• Mobile Suit Gundam: Char's Counterattack (Gyunei Guss)
• Ghost in the Shell (Togusa)
• Ghost in the Shell 2: Innocence (Togusa)
• Ghost in the Shell: S.A.C. Solid State Society (Togusa)
• Keroro Gunso the Super Movie (Zorori)
• Sakura Wars (Brent Furlong)
• Shrek (Donkey)
• Shrek 2 (Donkey)
• Millennium Actress (The Man of the Key)
• Disney cartoons (Donald Duck)
• Ninja Scroll (Jubei Kibagami)
• Beauty and the Beast (Beast)
• The Little Mermaid (Sebastian)
• Paprika (Dr. Osanai Morio)
• Pokémon: The First Movie (Mew)
• Pokémon: The Movie 2000 (Lugia)
• Pokémon 3: The Movie (Deibitto)
• Pokémon 4Ever (Hunter)
• Pokémon Heroes (Rosshi)
• Pokémon: Jirachi Wishmaker (Butler)
• Pokémon: Destiny Deoxys (Professor Lund)
• Pokémon: Lucario and the Mystery of Mew (Sir Aaron)
• Pokémon Ranger and the Prince of the Sea: Manaphy (Jack Walker)
• Kiki's Delivery Service (Officer, Announcer)
• Mulan (Mushu)
• Memories (Migeru)
• Lilo & Stitch (Stitch)
• Seri anime Ranma ½ (Ryoga Hibiki/P-chan)
• Robots (Fender)
• Saint Seiya Knights of the Zodiac: Legend of Sanctuary (Gemini Saga)
• Pokémon the Movie: Diancie and the Cocoon of Destruction (Ninja Riot)

• Space Battleship Yamato (Susumu Kodai)
• SNK vs. series (Mike Bison)
• Kingdom Hearts (Donald Duck, Genie, Sebastian, Beast, Mushu)
• Kingdom Hearts: Chain of Memories (Donald Duck, Genie, Beast)
• Kingdom Hearts II (Donald Duck, Genie, Sebastian, Beast, Mushu, Stitch)
• Rival Schools (Daigo Kazama)
• Seri Super Robot Wars (Gyunei Guss)
• Street Fighter Alpha 3 (Cody Travers, Mike Bison, Narrator)
• Xenosaga (Gaignun Kukai, Albedo Piazzola)
• Tales of Destiny (Johnny Sheeden)
• Rogue Galaxy (Desert Claw, Narrator)
• Drakengard (Leonard)
• Brave Fencer Musashi (Ed)
• Mario Kart Arcade GP 2 (Live announcer)

• I, Robot (Del Spooner)
• Independence Day (Captain Steven Hiller)
• Wayne's World (Wayne Campbell)
• West Side Story (Bernardo)
• Red Dwarf (Cat)
• Eddie Murphy
  • 48 Hrs. (Reggie Hammond)
  • Seri Beverly Hills Cop (Axel Foley)
  • Seri The Nutty Professor (The Klump Family)
  • Seri Dr. Dolittle (Doctor John Dolittle)
  • Showtime (Officer Trey Sellers)
• Seri Austin Powers (Austin Powers, Doctor Evil, Fat Bastard, Gold Member)
• Kung Fu Hustle (Sing)
• Disney's House of Mouse (Donald Duck, Mike, Mushu, Genie, Beast)
• The Adventures of Sharkboy and Lavagirl in 3-D (Mr. Electricidad, Mr. Electric, Ice Guardian, Tobor, Iceman)
• Shaolin Soccer (Sing)
• Spy Kids 2: Island of Lost Dreams (Romero)
• Spy Kids 3-D: Game Over (Romero)
• Speed (Jack Traven)
• Space Jam (Michael Jordan)
• Dark Angel (Logan)
• The Sum of All Fears (Jack Ryan)
• Back to the Future trilogy (Marty McFly)
• Bad Boys (Marcus Burnett)
• Bad Boys II (Marcus Burnett)
• Band of Brothers (Captain Lewis Nixon)
• Fight Club (Tyler Durden)
• The Fifth Element (Zorg, Ruby Rhod)
• Flubber (Philip Brainard)
• Full House (Joey Gladstone)
• The Mask (Stanley Ipkiss/The Mask)
• Max Headroom (Max)
• Mr. & Mrs. Smith (John Smith)
• Mary Poppins (Bert)
• Memphis Belle (Dennis)
• Seri Rush Hour (Carter)
• The Lord of the Rings film trilogy (Éomer)
• Who Framed Roger Rabbit (Roger Rabbit)
• Lemony Snicket's A Series of Unfortunate Events (Count Olaf)
• Stranger Than Fiction (Harold Crick)

• Profil resmi di Across Entertainment Diarsipkan 2009-07-24 di Wayback Machine.
• Profil di ANN Encyclopedia
• Koichi Yamadera di X