This guide will explain each mask and how to obtain them.
This mask is obtained by joining the Developer Group on Steam. The invite to it is obtained by being hired by Overkill Software. Once you are an employee, you also receive an invite to every mask group.
This mask is unlocked my doing something great in the PDTH Community. Something so great, that the developers see this and give you an invite to the Moderator Group on Steam.
Join the Vyse Group on Steam.
Complete every Non-DLC heist on the Overkill 145+ Difficulty unlocked at level 145. You will receive the “You are golden! Overkill salutes you!” achievement.