House ad for Showcase #101 [Hawkman] (June 1978); printed in Batman #300 (June 1978)
Comic cover art: pencils and inks by Joe Kubert
1961 ad designed and lettered by Ira Schnapp, repurposed for 1978, new lettering by Gaspar Saladino (?).
EDIT: A special thanks (and a hawk-winged Bull-Prize) goes to "Mighty" MarcusB, who gave me a link that showed me the original ads were published in DC Comics in early 1961. Using that as a lead, I found a couple examples in Justice League of America #5 (June-July 1961) and The Flash #110 (March 1961), ads hawking Hawkman, the original!
Thanks for your keen detective work, MarcusB! And in the words of Hawkman: Wheet! Wheet!