The headvoices (plus Mr. Samsa!!!)
Doughboys
So, in the first issue there's only one doughboy and it's D-boy. But he looks a bit different from how he looks for the rest of the series. He has long, black sleeves that would be given to Mr. Eff instead in the next issue. I'm not sure if this means that issue 1 takes place before Eff existed (in the bios it says that D-boy is two years older) or what.
For most of the series, D-boy has a white hat with columns of skulls and a black brim. It also has a little creepy face on it. I think this face was a way Jhonen used to sign his initials. He has 'FUCK' on his front, a black scarf, and three thin stripes on his arms with black gloves. He has spiral eyes with tears coming down, his nose has a dot and four squiggles, and his mouth is white with a black tongue.
Though the back cover of issue 2 shows a pile of skulls instead of individual towers.
Eff has a black hat with little ghosts and the brim has vertical stripes. His scarf is white and his front has a stripe and a box that says 'Z?'. He also took the sleeves D-boy had at first. His eyes are blank with a thick outline, arrows pointing away from the face and they're surrounded by squiggles or spikes, like a cartoon sun. He seems to have a pig nose and his mouth has a bunch of lines and may have arrows at the ends. His mouth is black with a white tongue. They both have black feet or shoes or whatever.
They also both have flat backs that are painted. D-boy has a spiral behind his head and Eff has... an arrow?? That would make sense.
When we do see them in color we see that Mr. Eff has purple on his hat and red eyes and scarf. D-boy seems to just be black and white. It seems the same at the end of I Feel Sick except the skulls on D-boy hat are black now. In the recent print Jhonen has changed quite a few things. The biggest thing is that D-boy now has glowing blue eyes to match Eff's red ones. Their hats are also very different. Now D-boy's has one big white skull as the top and Eff has a black skull with the teeth coming all the way down. D-boy has a little frowny face on the brim and Eff has a little smiley face. He also doesn't have the stripes anymore. Eff's front and gloves seem to be a dark green now (or it could just be the lighting or something). D-boy now has just two thicker stripes on his arms and has two squiggles on his nose and now it kind of looks like a mustache.
Reverend MEAT and Mr. Samsa
It looks like Meat and Mr. Samsa were planned to also be doughboys originally. One was named Senor Bondage and it says "the urge to give in to the mentality of being a physical being. Driven by organic whim." This sounds exactly like Meat. The other doughboy, Nil, which means 'nothing', says "The Little Creatures That Live Inside Us--Fashioned by dough or clay, from the things we hope no one can ever see." Not completely sure what that means, but Mr. Samsa IS a little creature.
Anyway, I think Jhonen changed it because he realized it would be really redundant if Johnny came back and once again had two doughboys talking to him. It would feel like nothing had changed. It was an extra good decision to have Mr. Samsa not even be a headvoice, but something Johnny could project his desire on to. Instead of being dragged back and forth by two opposing voices, it's Johnny himself and his desire to be emotionless like Mr. Samsa (which isn't true. bugs have lots of little bug emotions) vs Meat and his desire for Johnny to give in to all of his emotions. This is also shown in the fact that he doesn't trust Meat at all when he thought of the doughboys as his friends.
Reverend MEAT doesn't get a chance to change much. He's able to move around to some extent right away, making his burger disappear and making his eyes blank, like Eff. They also have stitch marks going up from them. His shirt can have different words on it, like Johnny's shirts, and he has sharp teeth and overalls. In I Feel Sick we see that he has red eyes, but then they get changed to a glowing pink. The pattern on his overall might be gone now and they might be red, but it's hard to tell.
Mr. Samsa is an immortal roach (or a series of roaches) and he stays that way. He hasn't shown up in group shots of the headvoices because he doesn't talk and is just a little bug who likes candycorn.
Nailbunny
Nailbunny hasn't changed at all aside from the one big change that happened in the comics. He was a dead bunny with a huge nail in him, but Eff rips his head off and now he's just a floating bunny head. He's blue and can fit on an ice cream cone.
Fetus in a Jar
It had one line in issue one where it distracted Johnny from killing himself by telling him that a funny commercial was on. Usually I would assume it's just some Early Installment Weirdness, but it showed up in a recent print with the other headvoices, so I guess it's canon. Now's it's in some other fluid-filled container and it looks like it was some oddity Johnny bought at a store or something rather than he himself finding a fetus somehow and just putting it in a jar.
