Grim Adventures Of Billy And Mandy, The
- Play as Boogey
- Successfully complete Mission 9 in Tier 4 in Mission mode to unlock Boogey.
- Play as Chicken
- Successfully complete Story mode with all characters and accumulate 10 hours of game play time to unlock Chicken.
- Play as Dracula
- Successfully complete Mission 5 in Tier 3 in Mission mode to unlock Dracula.
- Play as Eris
- Successfully complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Eris.
- Play as Fred Fredburger
- Successfully complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Fred Fredburger.
- Play as General Skarr
- Successfully complete Mission 6 in Tier 4 in Mission mode to unlock General Skarr.
- Play as Hoss Delgado
- Successfully complete Mission 9 in Tier 1 in Mission mode to unlock Hoss Delgado.
- Play as Jack O'Lantern
- Successfully complete Mission 9 in Tier 2 in Mission mode to unlock Jack O'Lantern.
- Play as Lord Pain
- Successfully complete Mission 9 in Tier 5 in Mission mode to unlock Lord Pain.
- Play as Mogar
- Successfully complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Mogar.
- Play as Nergal
- Successfully complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Nergal.
- Play as Nergal Jr.
- Successfully complete Mission 9 in Tier 3 in Mission mode to unlock Nergal Jr.
- Play as Nerglings
- Successfully complete Story mode with all characters to unlock Nerglings.
- Play as Pumpkin
- Successfully complete Story mode and deal out a total of 100,000 damage points to unlock Pumpkin.
- Play as Vikings
- Successfully complete Story mode with all characters and destroy every letter in the credits sequence to unlock Vikings.
- Alternate costumes
- Successfully complete Story mode with any character to unlock an alternate costume for that person.