I’ve kept wiki busy the last couple of days and enjoyed it immensely.

It has been interesting, but not surprising, how many of them have come from groups marginalized by the society of their day.

To quote an authentic Socialist, without caveats:

I do not want you to follow me or anyone else; if you are looking for a Moses to lead you out of this capitalist wilderness, you will stay right where you are. I would not lead you into the promised land if I could, because if I led you in, some one else would lead you out. You must use your heads as well as your hands, and get yourself out of your present condition.

http://en.wikipedia.org/wiki/Eugene_V._Debs

John Dewey, the shaper of the student-centered American educational philosophy.

More obscure, but Max Schactman (sp?), Michael Harrington, Irving Howe, and Sidney Hook. (Soem might argue with Hook, but he considered himself a democratic socialist ‘til the day he died). All with impeccable anti-communist credentials.

Orwell, though not American, is always a good one to throw in the face of wingnuts.

James Connolly (of the Irish Easter rising) worked for the IWW (the ‘wobblies’), as the IWW could give him a paying job, before returning to Ireland.

Jack London, as folks have mentioned above, is more problematic. In my mind, there’s a good chance that, given his racialist views, he would have done an Oswald Mosley had he lived longer.

More at:
http://en.wikipedia.org/wiki/Category:American_socialists

And let me add a few who were not socialists for their entire career, but either began or ended that way: Martin Luther King (at the end), Walter Reuther (at the beginning), Sidney Hillman (ditto) and A.J. Muste (likewise). And, as already mentioned, Randolph and Rustin.

By the way, what are the caveats to Debs?

Known for literary work in a sense—he was a journalist, but a very political and influential one—would be Lincoln Steffens. (And “The Autobiography of Lincoln Steffens” is an awesome book if you are interested in unintended consequences.)

King C Gillette (founder of Gillette company)

Horace Liveright (publisher)

Edward Bellamy (“Looking Backward”)

Partially due to German influence, the town had a socialist mayor and was the home of Socialist Presidential candidate Darlington Hoopes. The surrounding area is still quite red, although that means something altogether different in contemporary politics.

If I could clarify my request, while I am aware of, and appreciate the Roosevelts and those of a similar national stature (although Helen Keller was news to me) my particular interest is those who managed to make a contribution or attained a profile outside of literary or academic endeavour.