Are these illustrations done manually by hand or in Illustrator? Is there a easier way to reproduce these kind of illustrations?
While I think your examples are hand crafted scratchboard illustrations. If you are looking for something automated and quick, Alpha Plug Ins has the Engraver II plug in which is designed to generate some scratchboard-like appearance.
I think those are like comic book drawings, whether on paper or on Illustrator both cases they are manually drawn.
However there's an easy way to create something close to that on Photoshop using filters, here's how:
Open the desired image in Photoshop:
Play with the numbers (
Hope you find that useful :)