Bossman

Who is Bossman?
In Season 3 Bossman is a trauma that you see during Dex's dream sequence in Rehearsal. There were multiple Bossman in this sequence and interestingly enough Dex puts on a Bossman mask, right before you're guided to the next room (Jack's interrogation).

Bossman is your own personal trauma, whatever that may be.

He is most commonly seen in a koala mask.