First up, you have the Halloween II Clean Version, which is based on the beginning of Halloween II (i.e. the footage from the first Halloween). It's a clever way of giving you a Halloween I mask, without all the legal issues.
Next up you have the Halloween III Trio (Skull, Witch, Pumpkin),
The last remaining masks are from Halloween 6, Halloween H20 (not up for pre-order yet) and Halloween: Resurrection (not up for pre-order yet). Although not a favorite among most people, I personally love each one.
This is going to be the year for Michael Myers people and it's all thanks to Trick or Treat Studios.