Makoto Iwamatsu (often simply credited by the mononym, Mako) was a Japanese-American actor well-known for his numerous stage and film roles, such as Akiro the Wizard in the Conan the Barbarian films, as well as voice roles like Aku in Cartoon Network's Samurai Jack, and Uncle Iroh in Nickelodeon's Avatar. His roles were characterized by his rich, but gruff voice, always managing to sound wise. He passed away in July of 2006, a mere five months before the final episode of the series aired.
In Super Robot Monkey Team Hyper Force Go!, he provided the voice for Master Offay. It is unknown who they would have hired to replace him, as Mako had passed away prior to the airing of the show's final episode, which saw Offay returning for the canceled Season 5.