John Cusack and Sean Hayes have joined the voice cast of Exodus Film Group's CG-animated feature comedy, Igor for The Weinstein Co.

Cusack replaces Christian Slater on the project voicing the title character of Igor, a gifted scientist who is born with a hunch on his back and is forced to serve a cruel scientist named Dr. Glickenstein. The Hollywood Reporter says Hayes is playing Brian the Brain, a brain in a jar who is one of Igor's sidekicks and inventions.

The cast includes Jeremy Piven, Jay Leno, Jennifer Coolidge, Molly Shannon, Steve Buscemi and John Cleese. Chris McKenna wrote the screenplay for Igor; it's set for an October 24, 2008 release.