Mother Base Bonus Staff

In Metal Gear Solid V: The Phantom Pain, the player can unlock some bonus Mother Base staff, at most five in total, depending on how they preordered the game.

Canine
Canine is a Diamond Dogs Mother Base bonus staff member who can be unlocked by doing preorders from any store outlet for the game in Japan, or by getting the Day One edition of the Steam Version in the Global release. He or she is identified by their bright crimson hair and a Diamond Dogs tattoo on either their left cheek (should the recruit be male) or right (if the recruit was female).

Hound
Hound is a Diamond Dogs Mother Base bonus staff member who can be unlocked only by doing an extensive Xbox Games-related preorder for the Day One release for the game. He or she is identified by their possessing dark brown hair with a slight green tint and a tattoo near their right eye, regardless of gender.

Fox
Fox is a Diamond Dogs Mother Base bonus staff member who can be unlocked only by doing a preorder of the Bonus edition of Metal Gear Solid V: Ground Zeroes and inputting the voucher code into The Phantom Pain when it is released. He or she is identified by light brown hair that almost comes across as blonde and, as their name implies, a tattoo near their left eye that matches that of the FOX unit emblem.

Skull
Skull is a Diamond Dogs Mother Base bonus staff member who can be unlocked only by doing a preorder of Metal Gear Solid V: Ground Zeroes via GAME Tsutaya and inputting the voucher code into The Phantom Pain when it is released. He or she is identified by either a full set of white hair (if the recruit is female) or otherwise a shaved head (male) and overall, as their name suggests, possesses near their left eye a tattoo with a skull that bears some resemblance to the logo for the Militaires Sans Frontières, Diamond Dogs' predecessor, only the skull's "face" is facing forward instead of to the side.