Well it took 12 pages, but people finally mentioned the books I'd most recommend: The Spectrum Books, Scott McCloud's Understanding Comics, and Loomis' Figure Drawing For All It's Worth.
The Spectrum books are great for inspiration. There are many original concepts to browse through and study. What's more, they're all award winning, so you get a good idea of what you need to work towards, to survive in the profession.
Scott McCloud's book puts into perspective just what kind of art you can make, and why you'd choose certain styles/forms - realism vs. abstractions vs. icons. It's real genius.
Loomis' figure drawing books is unique in a couple ways. First, he presents a simplified mannequin that's easy to sketch from memory in different poses. He has some excellent pages on balance, and how to make figures in motion off balance to suggest movement. He's also a very eloquent writer. I've saved some quotes of his on rhythm, balance, movement, etc, for teaching. Then, there are tons of sketches in the book to draw from. They're mostly attractive young dancers, and he draws them mostly through pencil shading, based on light and shadow. It's the kind of work you could do from photos, and really Hogarth is more helpful for memorizing the figure. One plus is that he claims a teacher once told him he'd never make a good artist, and to give up. So if he can succeed, then, hopefully so can any dedicated student.
Hogarth's Dynamic Figure Drawing is great, but it lacks a couple Anatomy Atlas sketches that'd make it perfect. For those images, you have to get his Dynamic Anatomy, or some such, and flip to the back. He has all sorts of simple rules for lines of rhythm, how to view forms and shapes. His drawings don't look like real people - they're exaggerated to emphasize his concepts. Once you really understand that, and read along with each sketch, you learn a ton - better than most college courses on figure drawing.
Sarah Simblet's book on Anatomy is very pretty, but not nearly as helpful. The photos are beautiful. I tried to use them to study the anatomy - sketching the photos freehand, and then tracing over them, trying to place muscles in the right places, etc. There's just not enough info in the book to do it right. I had to guess way too often, even when I took those same sketches to a BodyWorks exhibit and stood in front of real bodies. The sketches just didn't make sense with them. She is good at drawing, but she makes the mistake of not labeling her sketches properly. You see a sketch of a thigh, and you don't know if it's the front or rear view, or which side is facing outwards, away from the body, and which is facing in.
Heinrich Kley's a really great illustrator. He has a couple sketches I use for teaching. One, of an Elephant ice skating, emphasizes gravity, and how to create the illusion of gravity in drawing. Another shows a Kangeroo with baby in pouch, both playing a harp. It's called The Prodigy, and it's really cute.
For inspiration in comics, there's none better than Bill Waterson. I put together some classes on cartooning, and Bill Waterson serves for every teachable lesson - facial expressions, twisting, posing figures, size as a dramatic effect, effective/dynamic page layouts, mixing drawing styles to enhance the story, even making entire comics without any dialogue, just going from one image to the next. Plus his dialogue's great, when he uses it.
David Cho is also a great cartoonist that shares many of the same qualities as Bill Waterson. What's the name of his series? Something similar to Bloom County... Something Meadows.
Anywho, Berkeley Breathed is great with Bloom County, making great fun of 80's mass culture and politics. If only he were still going. We need him to pick at GW.
Akira comics have some of the greatest drawings I've seen so far as suggesting motion. You can hear the metal hitting concrete and explosions just from seeing the drawings.
No one's yet mentioned some New England realists like Wyeth and Homer. They're great.
There are a ton more great artists out there, but I can't think of titles just yet.