Unlock Boogey
Complete Mission 9 in Tier 4 in Mission mode to unlock Boogey.

Unlock Chicken
Complete Story mode with all characters and accumulate 10 hours of game play time to unlock Chicken.

Alternate Costumes
Complete Story mode with any character to unlock an alternate costume for that person

Unlock Dracula
Complete Mission 5 in Tier 3 in Mission mode to unlock Dracula.Unlock Eris
Complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Eris.

Unlock Fred Fredburger
Complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Fred Fredburger.

Unlock General Skarr
Complete Mission 6 in Tier 4 in Mission mode to unlock General Skarr.

Unlock Hoss Delgado
Complete Mission 9 in Tier 1 in Mission mode to unlock Hoss Delgado.

Unlock Jack O'Lantern
Complete Mission 9 in Tier 2 in Mission mode to unlock Jack O'Lantern.

Unlock Lord Pain
Complete Mission 9 in Tier 5 in Mission mode to unlock Lord Pain.

Unlock Mogar
Complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Mogar.

Unlock Nergal
Complete Story mode with Billy, Mandy, Grim, or Irwin to unlock Nergal.

Unlock Nergal Jr.
Complete Mission 9 in Tier 3 in Mission mode to unlock Nergal Jr.

Unlock Nerglings
Complete Story mode with all characters to unlock Nerglings.

Unlock Vikings
Complete Story mode with all characters and destroy every letter in the credits sequence to unlock Vikings.