Knowing how to unlock characters in Back 4 Blood is important as, while there are eight to chose from, all with specific buffs, you only get four to start with. The final set of cleaners, Doc, Hoffman, Jim and Karlee are locked away at the start, and the game gives you no indication how you can to access them. Obviously that can leave you wondering what hoops you've actually got to jump through to get the full cast. Fortunately it's easy, if unclear, how to get a full complement of cleaners, so let's explain all...
How to unlock Back 4 blood characters
If you're wondering how to unlock Back 4 blood characters there's no trick involved, you simply have to play through a certain amount of the game to unlock Doc, Hoffman, Jim and Karlee. Act 1, The Devil's Return, consists of four levels which you'll need to clear with the starter roster before you can get all the Cleaners on your list. So that means getting through the opening missions with Evangelo, Walker, Holly and Mom to access the rest. So that's the missions Resurgence, Tunnel of Blood, Pain Train and The Crossing which need to be cleared.
That will see you escaping a town called Evansburgh with the starter Cleaners, and culminates with the explosive finale where you destroy a ferry and escape across a bridge. Once that's done you'll reach Fort Hope, and once there you'll get a cutscene that will introduce the final four characters. And that's all you actually have to do. There's no criteria or challenges, just advance the story far enough and you'll unlock all the Back 4 Blood characters. There's some useful team skills there too: Doc is a support character that helps with healing, Hoffman boosts ammo and offensive inventory, Jim helps with aiming and damage, and, finally, Karlee has a recon sense and boosts use speeds.