User blog comment:Hyaenidae/Pictures of Prothean and EDI squadmates./@comment-3053284-20120217113632/@comment-1691295-20120217131155

Apparently when the N7 Collector's edition was first announced, one of the announcements somewhere (EA.com/Press Release or something) accidentally mentioned "The Prothean". That's pretty good reason to assume he's the DLC character.