Sandman

Sandman man a member of the Justice Society of America. He wore a standard business suit and cloak and a fedora hat. His entire face iscoverred by a gas mask likely as his comic incarnation used a gas gun to combat opponents and required a gas mask to avoid putting himself at risk of exposure

It is likely the Wesley Dodds character, as it was primarily him known for being a JSA member and wearing the staple gas mask.