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 cast as the Green Goblin in Julie Taymor's Broadway production of Spider-Man: Turn Off the Dark before the role was re-cast.
He also has his own perfume called Cumming: The Fragrance.
Roles on Gargoyles
A shout out is made to him with the mention of the Celebrity Hockey player Cumming in "Estranged".