The 1st and 2nd Printings of this manual contained the Cthulhu and Elric (Melnibonean) Mythos. The 2nd - 4th Printings contain a thank you comment to Chaosium for the use of the material, even though the material was removed after the 2nd Printing due to an intellectual property copyright dispute.
Anecdotally according to Frank Mentzer at GenCon SoCal 2003, the Printings of this book were referred to internally at TSR as follows:
1st Printing: Squids, no thanks!
2nd Printing: Squids, with thanks!
3rd and 4th Printings: No squids, with thanks! (3rd has wizard logo, 4th has face logo)
Later Printings: No squids, no thanks!
Additional commentary on this aspect of the book can be found at: http://www.hahnlibrary.net/rpgs/faq/rgfdfaq4.html#E8
Dieties & Demigods has enjoyed numerous printings. Parties interested in the earlier Printings should definitely consult expert resources when purchasing or investigating specific, early printings.
The 1st - 4th Printings (titled Dieties & Demigods) feature the "old" cover by Erol Otus; the 5th and later Printings (titled Legends & Lore) feature the "new" cover by Jeff Easley.
1st Printing, 1980, contains 17 pantheons in 144 pages; wizard TSR logo
2nd Printing, 1980, contains 17 pantheons in 144 pages with "Special Thanks..." comment on page 4; wizard TSR logo
3rd Printing, 1980, contains 15 pantheons (back cover still says 17) in 128 pages with "Special Thanks..." comment on page 4; wizard TSR logo
4th Printing, 1981, contains 15 pantheons in 128 pages (back cover now says 15); face TSR logo - early versions retain the "Special Thanks..." comment, later versions do not; the cover background color on this Printing is shifted from purple toward blue
5th Printing, 1985, retitled Legends & Lore - contents otherwise identical to 4th Printing
6th Printing, December 1987 - identified on copyright page
7th Printing, April 1988 - identified on copyright page
8th Printing, April 1990 - identified on copyright page
Exhaustive information can be found at: