Alan Cumming
Alan Cumming was the voice of John Castaway in "The Journey" and was cast when Scott Cleverdon was unavailable. Cleverdon reprised the role in later episodes. Greg Weisman has also said that Alan Cumming would be his preferred actor to play the role of Staghart.
Alan Cumming is an accomplished actor, starring in "X2: X-Men United" as Nightcrawler; Roman Emperor, Saturninus in "Titus;" and was recently cast as the Green Goblin in Julie Taymor's Broadway production of "Spider-Man."
He also has his own perfume called Cumming: The Fragrance.