Out of this World Cartoonists
Space and Alien Cartoons by Australian Mark Godfrey on him smug mug page.
Star Man: A Visual Look at the Visible Sky by Jake Ryan
Astronomy Cartoons by Sidney Harris
Space Cartoons by Vlad Kolarov
Physics and Astronomy online recommends the work of Rick London.
Nick Kim's work includes Astronomy, Alien, Dr. Who and Science cartoons. His website is Nearing Zero.
Andy Reynolds' Astronomy Cartoons
Remy Bond Fly Me to the Moon Artistic Project
CSL Cartoon Stock - Astronomy Humor
Go to website. Type in astronomy as keyword (next to search images)
Toon Pool. This site has cartoonists from around the world. I've gathered some of my favorite astronomy related cartoons.
Space cartoons from The London Time Offbeat Cartoons - mostly aliens and Star Wars
Cartoon gallery Drunk in Space - compiled by The Orange County Register
Space Cartoons by Benita Epstein
Space Cartoons by Roodie Doodie
Cartoons and Sketches By Les Lamb (1913-2011). They are on Orwell Astronomical Society website.
Brian Zaikowski is the creator of Demented Denizens cartoons. He has alien cartoons and lots more.