I had an illustration teacher once who was incredibly obsessive, and in one illustration he had painstakingly copied each character of a typewritten letter in pencil so that it would look identical to a typewritten letter. The only way you would know this is because he would tell you. Though it was an impressive undertaking, it seemed totally unnecessary. Much like the exercise below.
This illustration is for the flyer for a comic book making class I'm going to teach to kids. Rather than cutting and pasting images of different cartoon characters, or even copying the characters from books, I took pains to duplicate the style of each cartoonist represented, and drew the characters in my own poses. Most likely, aside from other cartoonists, no one will ever know this unless I tell them.
The only one that I copied outright was Charlie Brown, because Charlie Brown is only drawn in a handful of poses anyway, and he's a bitch to draw. One squiggle or dot out of place, and it doesn't quite look like Charlie Brown, and even as it is I think it's just a tiny bit off.
Batman is probably the one that is mostly in my style since I suck at spot blacks and the feathering you typically see in superhero comics. I tend to rely a lot on color and tones to flesh out my line.
So from left to right: Tintin and snowy, Calvin and Hobbes, Astroboy, and just below him, Asterix, Naruto, the main character from something called "Fruit's Basket", Batman, and up front, Alice from a great strip called Cul-de-sac, and of course Charlie Brown.
I am told that Naruto and Fruit's Basket are the most popular manga right now, and the whole point of this flyer is to attract kids, so that's what I was going for. I don't know much about these characters, except that Naruto's costume is ridiculously elaborate. It looks like he's wearing a kind of 80s sweatshirt with some sort of pseudo victorian collar, and god knows what that thing is on his shoulder. I also couldn't bare to draw these characters in the dead characterless line that most manga are drawn in, so these guys were drawn with a brush. Otherwise I attempted to maintain the line style of the original characters.