They aren't. It's the artist usual art
Here is his FB account of the Artist you can see some other drawing:
Is the guy bottom left Penn Jillette?
The art in the comic is amongst my all time favorites, but the colour covers look too much like edited photographs or cgi. Case in point, is that Severus Snape on the left? All charaters on this remind me of scenes from movies I just can't place it.
it isn't. Only the main character is inispired by someone. (Sean connery)
Others are his usual art. He suffer a bit of the sameface syndrome though.