Fuck You Games Workshop

3 publications containing the term "Space Marine" long before Games Workshop got a hold of it. The first result is an extremely old one from 1952, talking about a new radio show for kids (presumably sci-fi) entitled "Space Marine". If Heinlein isn't considered a real enough entity in the sci-fi world to show that the term has been used outside of Game Workshop, then I don't know what is, and Alien was no slouch of a series either.

An ad about a new radio show called "Space Marine"
http://books.google.ca/books?id=XB8EAAAAMBAJ&pg=PA10&dq=%22Space+Marine%22&hl=en&sa=X&ei=xwgVUY-yKK6AygHmzoDwDA&redir_esc=y#v=onepage&q=%22Space%20Marine%22&f=false

Robert A. Heinlein's Space Cadet, contains two uses
http://books.google.ca/books?id=7wTPeOAhqPIC&q=%22Space+Marine%22&dq=%22Space+Marine%22&hl=en&sa=X&ei=sAgVUeWIFK_8yAGowoCQAg&redir_esc=y

Steve Perry's Earth Hive -  "Wilks was a space marine with a near-fatal flaw..."
http://books.google.ca/books?id=sCXpjx2yUSUC&q=%22Space+Marine%22&dq=%22Space+Marine%22&hl=en&sa=X&ei=awgVUZvmJKT4yQH7zoHYDA&redir_esc=y