
Quick answer — Kouji Yada voices Dr. Gero in Dragon Ball Z Kai, Oyaji in Den-noh Coil, Zeff in ONE PIECE FILM: STRONG WORLD - EPISODE:0 and 8 more characters.
Kouji Yada voices Dr. Gero (Dragon Ball Z Kai), Oyaji (Den-noh Coil), Zeff (ONE PIECE FILM: STRONG WORLD - EPISODE:0), Dohko (Saint Seiya: Knights of the Zodiac), Ryouhei Mikami (Another), Talan (Star Blazers: The Quest for Iscandar), Yoshizou Tada (Looking Up at the Half-Moon), Dr. Morimori (Mazinger Z) and 3 more.
Dr. Gero is voiced in Japanese by Kouji Yada.