Kirk voices Usui no Sadamitsu in Otogizoushi.
Kirk voices Gary in Gensô suikoden IV.
Kirk voices Tadakatsu Honda in Sengoku musô mushôden.
Kirk voices Plant Contra in Neo Contra.
Kirk voices Bootcamp in Scaler.
Kirk voices AWACS Thunderhead in Ace Combat 5: The Unsung War.
Kirk voices the soldiers in Death by Degrees.
Kirk Thornton voices Kevin Ryman and other additional voices in Resident Evil Outbreak: File #2.
Kirk Thornton is credited in the console game Kingdom Hearts 2 as the voice of Saïx, one of the members of Organization XIII.
Kirk voices Xiahou Dun and Meng Huo in Shin sangoku musô 4.
Kirk voices Hideo Kuze in Kôkaku kidôtai: Stand Alone Complex 2nd Gig.
Kirk does some voicing in Dungeons and Dragons: Dragonshard.
Kirk is best known for his voicework of men who are really grouchy and/or tough like in the military in animes and video games.