[SJackson]

Spencer dates to Taki's Magazine, American Conservative before that. It's not entirely clear to me what the alt-right is, but in would certainly encompass those sites and many more distasteful. Spencer did found alternativeright.com. IMO Breitbarts description is correct. The supposedly offensive article published under Bannon is Establishment Conservatives Guide to the alt Right

[spankalib]

I’m not at all comfortable with the nazi salutes.
http://www.theatlantic.com/politics/archive/2016/11/richard-spencer-speech-npi/508379/

[TBP]

The Establishment Conservative’s Guide to the alt-
Right, whcih as youo noted was published by Breitbart, cited Spencer as “the leading thinker” of the alt-right. Spencer is the one who leads this bunch of malcontents doing the Nazi salute.

Bannon told Mother Jones that he had made Breitbart into “the platform for the alt-right.”

A movement led by Spencer, and which counts among its leaders the likes of Jared Taylor. people who lead movements and websites that can’t be cited here at FR, and who espouse attitudes that are banned here at FR.