William McCoy (1932-1974) was one of the many puppeteers who portrayed Sea-Dog.
Not much is known about his career, except that his deep Southern accent led to him being cast as the titular character in Fisherman Fred.
After Fisherman Fred wrapped production, McCoy did the voice of Sea-Dog in one episode in Candle Cove. After that, he retired and moved to Wyoming to start a farm. Three years later however, he was mauled to death by his pet Alaskan Malamute, making him another suspected victim of the Candle Cove Curse.