"The Secret Origin of Mister Spectre" from Secret Origins vol.3 #15 (DC, 1987) by Roy Thomas and Michael T. Gilbert
I loved Secret Origins, the perfect companion to the same era's Who's Who, especially once it became double-sized to insure a Golden Age character every issue. It seemed to me the ones where they broke that format and focused only on modern characters were never my favorites. Towards the end of the run, though the major characters had perhaps been expended, Secret Origins continued to shine with surprising thematic issues (headquarters! apes!) and quirky origins (Ambush Bug's! Flash of Two Worlds!). It was one of my favorite DC series ever, and I miss a DC Universe in which it could exist.