Dean Toadblatt is a guest character from the show, The Grim Adventures of Billy and Mandy, on Cartoon Network. Toadblatt is a a giant, toad wizard that runs Toadblatt's School of Secrecy. He prefers the Gunderstank House, which is his preferred favorite, and he despises Weaselthorpe. He also despises Nigel Planter, a member from Weaselthorpe.
In his debut, he was voiced by John Vernon. He has been voicing him from season two to five until he passed away when the show was still in production. In season seven, he was replaced by Ronnie Schell.
Between these two, I have to go with Vernon. Vernon was pretty much a young Toadblatt while Schell was an old Toadblatt. Also, Vernon did more voice work for Toadblatt. Schell did a good job as a replacement.