In the Brave and the Bold #36 (April 1961), one of Hawkman’s repeating enemies is introduced: the Shadow Thief. Carl Sands learns how to separate himself from his shadow, then rescues a dying alien who gifts him with a “dimensiometer”, which can let him control his shadow and manipulate the world around him. The alien later recants and asks for the machine back, since overuse will trigger a new Earth ice age.
Carl Sands doesn’t buy any of that crap and embarks on a criminal career as The Shadow Thief. That is, until Hawkman and Hawkgirl defeat him, destroying the dimensiometer. This is the last issue of The Brave & The Bold with Hawkman try-outs until the Hawks make their debut in their own magazine.