The Submission Guidelines for every Comic and Manga Publisher in the Universe

I found this website ages ago and probably unwisely assumed that everyone knew about it, so if you haven’t seen it before, this is an extremely useful resource.
DARK HORSE still welcomes your submissions, and all submissions will still be reviewed. Dark Horse has one of the most detailed and elaborate submission processes out there. They mean business. You’ll need to download the Submission Agreement and make sure you send in a signed copy along with your other materials. Be sure to read through all of their submission pages as there’s an amazing amount of useful info on there.
Writers will need to send in a synopsis as well as the full script for a short story or the first 8 pages of a full-length series. Artists should send in 5-6 consecutive story pages. Same goes for inkers. Dark Horse will provide sample pages to ink if you send in a large 11″x17″ self-addressed stamped envelope.
Colorists need to send in 5 pages of sequential art. They want to see how you handle different types of storytelling. Letterers can submit at least 5 pages of story to show diversity of balloons and sound effects, as well as font choice. In addition, please show examples of italicized and bold text.
DC COMICS has an annual TALENT SEARCH? They only look at artists and you need to hit up either the New York Comicon or the San Diego Comicon. The DC TALENT SEARCH program is designed to offer aspiring artists the chance to present artwork samples directly to the DC Editors and Art Directors. The process is simple: during your convention visit, drop off photocopied samples of your work. If DC like what they see, a time is scheduled for you the following day to meet a DC editor personally to discuss your portfolio.
Sorry writers – no dice. At this time, DC Comics does not accept unsolicited writing submissions.
IMAGE COMICS only publishes creator-owned material! Only submit original material, not something utilizing existing Image characters. Image Comics accepts only PROPOSALS for new comic series or graphic novels, etc. For writers DO NOT SEND your script or your plot unaccompanied by art — it will be discarded, unread.
They DO ACCEPT inking, pencilling, lettering, or coloring samples. They’ll keep them on file if they’re interested for future consideration and may hook you up with other creators if and when the occasion presents itself. The books Image publishes are creator owned/creator generated properties and they DON’T PAY PAGE RATES. It will be up to you to strike a deal with whomever you end up working with. Image takes a small, flat fee off the books they publish and the rest goes to that comic book’s creative team. How that profit is split up is entirely up to the creators involved.
A PROPOSAL should contain A typed, ONE PAGE, synopsis of the ENTIRE series or story arc. Send photocopies of fully INKED and LETTERED pages (any size). AT LEAST five pages that are fully inked and lettered. Color is OPTIONAL. Include a cover mock-up.
MARVEL COMICS is still no longer looking at submissions.
Their original guidelines paraphrased as they were listed in early 2009 : Writers send an inquiry letter, detailing your writing experience and why you would like to write for Marvel. Based on your inquiry, they may ask you to submit a sample of your work.
Artists – If you have a website with your work on display, please send us a link to your website using the Marvel Art Submissions email address. Submit no more than 5 pages of sample artwork. If you submit by mail, send clean 8 1/2″x11″ photocopies of your sample pages.
3 or 4 pages of sequential action, 2 or 3 pages of character-driven storytelling and 1 page of cover art or iconic character poses.
For Inkers: Don’t send samples inked over your own pencils. Send copies of the original pencils along with your inks so they can see what you started with. Use samples done over several different pencilers. For Colorists: Don’t send samples colored over your own line art.

**UPDATE – Marvel has now posted the following on their submissions page:
Due to an unprecedented number of unsolicited art and writing submissions, Marvel has altered its open submissions policy effective immediately. Marvel has remained the only major publisher to continue accepting open submissions, however that practice has been halted as we review our strategies for accepting future submissions.