Bill Scott was the original voice of Gruffy, Toady, and Sir Tuxford. After he passed away, Corey Burton voiced Gruffi and Toady for the rest of the series.
Roger C. Carmel voiced Sir Tuxford in Season 2, while Brian Cummings voiced him starting in Season 3.
Paul Winchell left the series after Season Five, so Jim Cummings took over as the voice of Zummi.
Also, the voice artist for Cavin has changed regularly during the course of the show's run as the artist in question grew up and his voice broke and had to be replaced. In this case, Christian Jacobs first voiced Cavin during season 1, then Brett Johnson did the honors in season 2, followed by DavidFaustino in season 3, then Jason Marsden in seasons 4 and 5, and finally R.J. Williams in season 6.
Talking to Himself: All the way in the Mexican Spanish dub, especially between Sunni and Calla, who are very good friends, albeit it's not too notable because all the voice actors managed to sound too different between each character.
And in the normal version, Michael Rye was both Igthorn & Gregor, so a lot of episodes have him yelling at himself. Ditto with Gad & Zook who often converse with each other, as Will Ryan voiced both.
In the Norwegian dub, "Marvin" (Zummi), "Gruffi", "Gumle" and Paddvart are all voice by the Uncle of Children's TVnote as he's called due to his heavy work in translation, narrating, voice acting, directing and production of dubbed children's material, Harald Mæle, though its helped by him being a Man of A Thousand Voices.