VGFacts

In the arcade room you can see multiple posters on the walls. Almost all of these posters refer to other games from the same developer.



The most obvious references are Meat Boy


Time Fcuk


Gish


Tri-Achnid


Spewer


and Coil


All of these are Edmund McMillen's previous games he developed prior to Binding of Isaac.

Now, all we have left are the poster with the red text that says "Isaac", the blue-ish picture with the smiley face and the bloody picture which is most likely of Isaac himself.

I think the blue one is of Aether. The color scheme is similar and it is one of Edmund's previous games.