INDUSTRY: SF/F/P Publishing Houses

For those of you on the journey to publication I thought I’d pass on knowledge gathered over many years concerning single title publishing houses, specifically in the mainstream sci-fi/fantasy/paranormal and romance genres.
Starting out I knew of a few major houses, mostly from looking at the spine of the books on my shelf but, over time and with the help of other writers and now my agent, I’ve sifted through the information and think :-) I have a better handle on it.
A couple of great research websites include Speculative Fiction Book Publisher Markets website - they lists many print & e-publishing houses, Preditors & Editors - they have a huge listing of publishers, in alphabetical order and with recommendations and warnings, and Book Crossroads - a directory of e-publishers with submission guidelines.
I hope you find the lists useful in your quest for publication. Unless otherwise indicated the publishing houses are based in the US market and are mostly listed as Publishing House, Company and/or Imprint name. Googling the names should give you links to their websites.

Mainstream SF/F Houses
Penguin Putnam :DAW
Penguin Putnam: ACE & ROC
Random House: Doubleday, Bantam Press, Black Swan, Bantam & Corgi (UK)
(Random House)Ballantine: Del Rey & Spectra
Hachette Book Group: Grand Central Publishing: Orbit Books
Dorchester: Tor
Pocket Books: JUNO Books
Baen Books
Penguin: Viking, Sphere, Orion & Signet (UK)
HarperCollins: Voyager & Angry Robot (UK)
Prometheus: PYR
Arrow Books: Legend (UK)
Solaris (UK)
BL Publishing (UK)
Victor Gollancz Inc: VGSF & Magnet (UK)
Mushroom eBooks (e-publisher)

Romance SF/F/paranormal Houses
Harlequin: LUNA fantasy imprint
HarperCollins: EOS fantasy imprint
HarperCollins: AVON paranormal romance imprint
Penguin: Berkley Sensation & Jove imprints
Penguin: Signet novel imprint
Penguin: NAL romance imprint
Hachette Book Group: Grand Central Publishing: Forever paranormal romance imprint
Kensington: Zebra paranormal romance imprint
(Macmillian) Tom Doherty Assoc.: Tor romance imprint
(Macmillian) St.Martin’s Press: St.Martin’s Paperback romance (US)
Random House: Bantam Books romance imprint
Dorchester: Leisure paranormal romance imprint
Dorchester: Lovespell paranormal romance imprint
Simon & Schuster: Pocket Star Books imprint
Medallion Press: Jewel Imprint Sci-Fi romance
Hachette Book Group: Little, Brown Book Group: Piatkus (UK)
Wild Rose Press (e-publisher)
Ellora’s Cave: Romantica imprint (e-publisher)
Samhain Publishing (e-publisher)
Loose Id (e-publisher)
Wings e-Press (e-publisher)
Whispers Publishing (e-publisher)
New Concepts Publishing (e-publisher)

By no means is this a complete list - I’m sure I’ve missed many but it’s a place to start. You’ll have to do the leg-work to find out more about them and their latest submission guidelines :-) .
Happy submitting!