Quick answer — Takuo Kawamura voices Hassan-i-Sabbah in Fate/Zero, Kitazawa in Baki the Grappler, Hachisuke Takamizo in Happiness! and 1 more characters.
Takuo Kawamura voices Hassan-i-Sabbah (Fate/Zero), Kitazawa (Baki the Grappler), Hachisuke Takamizo (Happiness!), Gwen (Togainu no Chi).
Hassan-i-Sabbah is voiced in Japanese by Takuo Kawamura.
