I successfully used an early online version of Voice.AI for an animation, isolating various snippets of Walt Disney's voice from background music.
Now they are offering the beta of an impressive voice changer.
I just got started with the software, so I have only tested the politician (GW Bush) and Popstar voices but apparently a subscription will get you access to many, many more choices.
VOICE.AI voice changing software
Animating now to life itself --Walt Whitman