Many heroes and villains wear a mask, and several villains were just called that: The Mask. Few last more than an issue or two, but the biggest legacy belongs to Nina Close, an enemy of Wonder Woman. She was an abused housewife who killed her husband; later incarnations expand her into an avenger for the abused.
The first character to use the name was an enemy of Spy Smasher. Created by Bill Parker and C.C. Beck, he first appeared in Whiz Comics #2 (1940). Nina Close was created by William Moulton Marston and Harry G. Peter, first appearing in Wonder Woman #24 (1947).