Tarzan is Batman (Secret Origins of Batman Part 5)
The first thing that needs to be pointed out is that the above black & white illustration is not by Henry Vallely.
For years I've looked at the iconic pose of Batman in his first published origin in Detective Comics # 33 (November, 1939) and known it was not purely from the imagination of Bob Kane. Not only had I previously found several other illustrations that Kane (or whoever was ghosting for him) had swiped from the pages of Big Little Books illustrated by Vallely, but frankly that pose was just too good to be Kane. So I've long had the belief that that particular pose of the Dark Knight crouched on a roof top was simply another Vallely illustration that I had yet to discover. A few years ago I became aware of Large Feature Comics No. 5, published by Dell in 1938, the bulk of which consisted of reprints of 60 Tarzan story strips from 1929 and is considered to be the first full comic book devoted to Tarzan in the comic book format. According to one source, in addition to the Hal Foster strips, it featured additional art and splash pages by Juanita Bennett. Another source attributed these supplementary drawings to Henry E. Vallely. Given the rarity of the book it wasn't until a few months ago that I was able to acquire a copy for myself and determine the truth: in order to enhance the continuity of the stories, Henry E. Vallely added one additional panel per page, along with ten full page chapter drawings. However, the pose appropriated for Batman's origin (found on page 42, panel 4) can not be credited to Vallely, but rather to Harold "Hal" Foster.
Tarzan® is © Edgar Rice Burroughs, Inc.
Batman is © DC Comics