Per Joe Orlando, from an interview in Comic Book Artist #1: "Carmine gave me the book (House of Mystery) and I remember that I drew the first cover from Carmine's layout." On The Drawing Board #66, April 1968, credits Roussos with cover art. Nick Caputo suspects Orlando penciled and Roussos inked the cover.
House of Mystery: The Bronze Age Omnibus Vol. 1 credits layouts to Infantino, pencils to Orlando, and inks to Roussos.
Previous indexer credited Nick Cardy, who is erroneously credited in Showcase Presents: The House of Mystery (DC, 2006 series) #1 and the book The Art of Nick Cardy, along with Carmine Infantino and George Roussos on inks.
Logo design credit from Dan Greenfield (through Mark Waid via 13th Dimension.com website, http://13thdimension.com/13-logos-a-gaspar-saladino-salute/, retrieved 7 August 2016).
Phantom Stranger-esque character
Writer credit from Showcase Presents: The House of Mystery (DC, 2006 series) #1.