I've loved comic strips as far back as I can remember, particularly Calvin and Hobbes and The Far Side. But in the last few years, I've discovered a whole lot more comics to my liking, and many that appeal to those of a scientific mindset.
xkcd may be the first of the Internet-based comics to break through into the mainstream, on the basis of its strong appeal to people interested in science, technology, humor, and sometimes relationships. It has now been around for almost four and a half years, amassing nearly 700 strips and is one of the most successful online comics (a.k.a, "webcomics").
If you want humor that is even more deeply connected to math and physics, try Abstruse Goose. One of my favorites is called All You Zombies.
I also enjoy this web comic about Charles Babbage and Ada Lovelace and their giant Difference Engine. And crime-fighting.
My current favorite online comic is Dresden Codak. The artwork is gorgeous. Every comic has an interesting idea in it (often something about science or philosophy), and it is relentlessly inventive, unafraid of trying new things.
You can support independent comic strips like this by buying their merchandise. (I do!) You can currently buy Dresden Codak comic strip prints and T-shirts and soon there should be a Dresden Codak book, compiling the artist's work.
There are of course many comic books which use the medium simply for explaining scientific concepts, Larry Gonick's Cartoon Guides to Everything being the best-known example.
Two-Fisted Science by Jim Ottaviani is a comic book with many different stories, all featuring real scientists and mathematicians, including Einstein, Newton, Galileo, Leibniz, Bertrand Russell, Bethe, Pauli, Heisenberg, Bohr, Oppenheimer, and Feynman!
Bertrand Russsell is also featured in Logicomix. I am currently reading it and will post a review when I'm done.
Thanks to some combination of increases in the role of science in society, interest in science, and leisure time, we now have a lot more opportunities to consume science-based literature and entertainment. Enjoy!