Perhaps the coolest Golden Age character DC had was the Sandman. He had that classic Film Noir look to him and his stories had that great dark crime novel feel to them. First drawn by Creig Flessel, Wesley Dodds' alter ego had a good run in the 40's until he was revamped by the Simon and Kirby team later in the decade, turning him into more of a generic superhero. I had the pleasure of meeting Mr. Flessel at a convention in 1994 and he was generous enough to do a sketch of his signature character for me.
Flessel just recently passed away and he will defintely be missed. The cover above of #60 was cover dated March, 1941.