Jack, a headless prankster from Grim's past, uses Billy to steal Grim's scythe so he can destroy Grim and take over the world with demons from the Netherworld.
| Actor | Role |
|---|---|
 Grey DeLisleMandy/Granny/Cowgirl (voice) | Mandy/Granny/Cowgirl (voice) |
 Greg EaglesGrim/Spirit/Knight (voice) | Grim/Spirit/Knight (voice) |
 Richard Steven HorvitzBilly/Guy (voice) | Billy/Guy (voice) |
 Wayne KnightJack (voice) | Jack (voice) |
 Vanessa MarshallIrwin/Toilet Paper Woman (voice) | Irwin/Toilet Paper Woman (voice) |
 Billy WestGiant Pumpkin/Lumber Jack/Announcer/Cell Phone Guy (voice) | Giant Pumpkin/Lumber Jack/Announcer/Cell Phone Guy (voice) |