I think Roy had the idea for the film way back in the mid 80's but Katzenberg was totally turned off by it. (rightly, IMO) Because of his lack of interest F: 2000 wasn't greenlit until after he left (October 1994). (Another example of Eisner kissing Roy's a**)The reason it took 15 years to make Fantasia 2000 is because the segments were done inbetween features as busy work.
For those ten years it was an independent project done by Roy and some animators, almost completely out of Katzenberg's juristiction.
Jim Hill Article via The Laughing Place
So that's how Musker and Clements found themselves in a recording session with James Woods, fumbling for a handle on Hades. James was looking for some sort of direction. So Ron and John explained that the Lord of the underworld was a powerful figure who was charming but ruthless, capable of doing anything he had to to get ahead.
"Sounds like some studio executives I know," Woods joked.
And that - my friends - is the real secret behind James Woods' version of Hades, Lord of the Underworld. In order to eventually earn the right to make Treasure Planet, Ron Clements and John Musker made a deal with the devil (AKA Jeffrey Katzenberg) to make Hercules first.
Now it's Halloween week 1995. And James Woods has just handed Ron & John the ultimate in-joke to slip into Hercules. After all, what better way is there for Musker and Clements to honor the man who insisted that they make this film than by placing a caricature of him into the movie?
That's right. Jeffrey Katzenberg - in all his smooth talking, schmoozy glory - served as Woods' model for his performance as Hades, Lord of the Underworld.
You want proof? Go find a picture of Disney's Hades. Then take a closer look at his long face, sharp features, intelligent eyes and balding head. Now draw a pair of glasses on the Lord of the Dead 's face.
Does this demon now look sort of familiar?