The Default Path where your Characters' Data Files are kept are the following:
Windows: C:\Program Files (x86)\Steam\steamapps\common\Move or Die\Lib\Assets\Characters
Mac: ~\Library\Application Support\Steam\steamapps\common/Move or Die\Lib\Assets\Characters
Linux: ~\.local\share\Steam\steamapps\common\Move or Die\Lib\Assets\Characters

Feel free to explore the Files, pick the characters you might want to play as (using the included .Png files), because as weird as it seems, all of them can be used in-game!

As you can see, there is plety of Characters you don't get to play with by default, a large percentage of them are just inactive, you can now unlock this Character roster and load these files so you can play with them!

• Apolloz
  
• BasicallyIDoWRK
  
• Carmichael
  
• Carnage
  
• D4
  
• D20
  
• DaithiDeNogla
  
• DRKendo
  
• Gavin
  
• H2ODelirious
  
• Jack
  
• JacobLincke
  
• Jake
  
• Jeremy
  
• Jimmy
  
• Kappa
  
• Lirik
  
• Michael
  
• MrHappy
  
• Nico
  
• PapaFranku
  
• RawrSnacks
  
• Renee
  
• Ryan
  
• Sam
  
• SideArms
  
• Wren
  
• Xelu

As you can see it is quite the long list... you can now pick whichever you want (or all of them!) and proceed unlock them.

Pretty much like in the game "Speedrunners" where you can type in a secret name on the chat to play as a secret character, you can enter the names you want from the list (no need for the Developer Console) anywhere in the game, and if you did it correctly you will hear a *Ding* sound wich means you can now access that character trough the Character Selection Screen!

Say I wanted to unlock Kappa, I would start up the game, I would type "K" followed by "A", a "P", another "P", and finally an "A" (That is K-A-P-P-A without the dashes) on my keyboard right after the game launched, or in the Character Selection Screen If I so desired. Then I would proceed to Pick my character for Local/Online play, and then just play the game while everyone stares with envy at my secret unlockable!

Step By step:
1- Pick a name from the list
2- Open up the game
3- type in the name of your desired Character
4- look for that Character now in the Selection Screen!

-===Keep in mind that these changes are only applied while running the Game, you will have to imput the names once again after closing it, so I encourage you to bookmark this guide for easy access. ===-

Shoutout to the guys in This Reddit Post for sharing their knowledge.
I couldn't find the information anywhere else, and decided to create this guide to help the community!
Feel free to contribute/ask/rant down bellow!

After you successfully managed to Unlock one of the Characters you will hear a Ding sound, This means you can then proceed to select them in the Character Selection Screen (works both locally and in multiplayer).

Keep in mind the access to these unlocked characters is limited to the current playsession, so you will have to unlock them again if you want to use them after you close the game. You will not (and probably never will) be able to get these Characters on your Inventory, that means you won't also be able to trade them nor sell them on the Market, they are restricted to your local files, and the method of unlocking them only grants you access to those files.

There is also the option to modify an already existing Character's looks to make it unique, or creating new Character's all toghether! (your own mod)

For simplicity sakes I'll just cover the first one.

• Grab the Character Folder of your choice and take the ".png" file.
  
  
• Open up your favourite image editor ( I suggest Pixlr Online) and open up that file.
  
  
• Start editing the parts of the character following it's structure (draw over the existing body parts, mind the gaps bewteen each of them, while also keeping not switching parts arround, keeping legs as legs for example)
  
  
• Then just save your progress replacing the old ".png" file in the folder (keeping the same name) and you should be good to go!
  
  
• Enjoy your custom made avatar

Keep in mind changes to any character will only be displayed on your machine, while it might look as the original modified character or another's machine!