So. This isn't an OC theory. That one will be next. And this is just gonna hbe all over the place.
This is a BATIM theory.

Now, from what I've gathered from MatPat. Alice Angel is Susie Campbell and Alison Pendle (Yes, I looked back at her tape in Ch 3 to figure out her last name) and that Norman Polk is 100% the Projectionist. But we have never really covered the Butcher Gang, Boris, or even Bendy in general.

Bendy:

Now I know that everyone says that Bendy is Joey Drew and I can see it happening. Yes we have evidence but the guys at The Meatly Games secretly put in a hidden audio for Bendy's voice. It's only in Chapter 2 when he's chasing you. If you listen closely while running away, he says "Let Me In!" and him laughing from the sounds of it. I found it on a video and I went to go hear for myself. So I looked up the non-commentary video of Chapter 2 and heard it.

This is 100% real. And now. Compare Joey Drew's voice to Bendy's:

OK, so I hear something between them. But maybe Joey Drew was just killed by Bendy and he took his soul-
OK now that's just crazy... right?

Actually, there's no proof. And it is likely that HENRY created Boris. Not Bendy. Joey had to have created Bendy? Because it makes sense if Joey really is Bendy.
BUT
There is a chance you will get this screen in Chapter 1:

The dancing demon is right by Henry's desk..
If Joey is Bendy, then he must be waiting for Henry at his desk if that's true.
And have you looked at Bendy's model in the game, you can CLEARLY see that both his eyes are covered up by the melted ink, and since Henry no doubt is covered in ink from head-to-toe, Joey/Bendy must think we're Alice. Since if you have seen the first appearance of Alice in her room when she jumpscares you, you both are at eye-level. The same height. So if Bendy we're to be looking at us, he would think we're Alice.

Sammy Laurence:

Didn't expected this one eh? Well, he isn't dead.
No. He is very much alive.
There is an easter egg in the recent Chapter that if you guys don't know already. In the stairwell, there are instruments that easily give away that they're Sammy's.
If you put in the sequence:

Drum
Bass
Fiddle
Piano
Drum

You get this:

He's alive. Which explains THE CHAPTER 4 TEASER ON TWITTER

(Better pic:)

You can see obvious references to Sammy:
The banner, the shrine, the record player, and an inkwell

The banner has his famous line
The shrine for worshipping Bendy
The record player symbolizing a musician or music director
And the inkwell for Sammy's ink body.

Is that all?
Just one more:
In the update for Chapter 2, you know how there was a puddle of black ink seeping though the door when Sammy was "killed" before?
It's gone now. And if you do a bit of hacking.
You see Sammy alive and well.

For Boris, MatPat already explained him.
As for the Butcher Gang, there is NOTHING that tells us about them.

(TKDitto613 >:3)