 
He is known for playing tough or grouchy men in dubbed anime and video games. His career includes Hotohori in Fushigi Yūgi and Jin in Samurai Champloo. He also played numerous cameos and minor characters in Rurouni Kenshin, in addition to the major character of Hajime Saito. He also does Don Patch in Bobobo-bo Bo-bobo as well as Gabumon and other voices in Digimon. He is even the English voice of Jet Link in Cyborg 009, the Narrator in Bleach, as well as Kisame Hoshigaki in Naruto and its sequel, Naruto: Shippuden. Kirk is now the official voice of Shadow the Hedgehog as of the 2010 release Sonic Free Riders. According to Anime News Network, Thornton boasts the most credits of any male voice actor who does English language dubbing, and in the field in general, is second only to Wendee Lee in total credits. To date he has been in over two hundred voice-over productions for Japanese animation