Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (50 p.m.a.), Mainland China (50 p.m.a., not Hong Kong or Macao), Germany (70 p.m.a.), Mexico (100 p.m.a.), Switzerland (70 p.m.a.), and other countries with individual treaties.
It was created for publicity purposes-distribution to the media. The image was meant to bring attention and publicity for the personalities pictured, and the film in which they starred.
Film production expert Eve Light Honthaner in The Complete Film Production Handbook, (Focal Press, 2001 p. 211.):
"Publicity photos (star headshots) have traditionally not been copyrighted. Since they are disseminated to the public, they are generally considered public domain, and therefore clearance by the studio that produced them is not necessary."
"There is a vast body of photographs, including but not limited to publicity stills, that have no notice as to who may have created them." (The Professional Photographer's Legal Handbook By Nancy E. Wolff, Allworth Communications, 2007, p. 55.)
"Publicity Photos (star headshots) older publicity stills have usually not been copyrighted and since they have been disseminated to the public, they are generally considered public domain and therefore there is no necessity to clear them with the studio that produced them (if you can even determine who did)."