Humphrey Bogart and Ingrid Bergman in a scene from the classic movie Casablanca. (WENN.COM)

In the glory days, Hollywood studios had obvious personalities. Without seeing the logo, you could often recognize a Warner Bros. movie of the 1930s and '40s -- gritty and noirish, with stories torn from newspaper headlines.

Criminals populated the screen as Warners became known as "the gangster studio." The studio's movies often defied censors who imposed their rigid values starting in mid-1934. The heightened realism of Warner movies scared and excited audiences. Fast-talking, quick-witted, gun-slinging men such as Edward G. Robinson, James Cagney and Humphrey Bogart became superstars. Bette Davis, Lauren Bacall and Barbara Stanwyck were their femme fatales.