I had previously last seen these sometime prior to 2007 and have cobbled this checklist together from those and a larger 2011 purchase that brings the total count to 23 31* known film stars in this set. My best guess is that this isn't all of them, but I'll just have to keep on buying to see if I can discover who's left to collect!
*Thank you again to contributor Amit Benyovits who contact me with an additional 8 names and images after I originally posted this to bring the known number of pieces in this set to 31.
There's nothing to ID these except for each actors' name at the bottom left and studio at the bottom right inside the portrait. Each one of these measures 5-1/2" X 6-1/2" with the black & white portrait inside the thick cream colored borders measuring 4" X 5". The paper is about the same stock as a magazine cover. The backs are blank.
I'm calling them premiums based on the lack of information. My gut tells me that they were likely a giveaway with a product or perhaps an item offered through one of the movie publications of the period.
At the time of the creation of this page I'm offering my most recent batch of these at auction on eBay.
Gallery
The following gallery includes images of each of these 23 premiums that I have handled. Just click on any image to open to full size and from there you can scroll through them all.
Checklist of All Premiums Shown in Gallery
Fred Astaire - RKO Radio
Freddie Bartholomew - 20th Century-Fox
Joan Blondell - Warner Bros.
Charles Boyer - United Artists
George Brent - Warner Bros.
James Cagney - Warner Bros.
Claudette Colbert - 20th Century-Fox
Gary Cooper - Paramount
Joan Crawford - MGM
Bing Crosby - Columbia
Marlene Dietrich - Paramount
Irene Dunne - Universal
Kay Francis - Warner Bros.
Clark Gable - MGM
Greta Garbo - MGM
Jean Harlow - MGM
Katharine Hepburn - RKO Radio
Leslie Howard - Warner Bros.
Ruby Keeler - Warner Bros.
Myrna Loy - MGM
Jeanette MacDonald - MGM
Victor McLaglen - 20th Century-Fox
Robert Montgomery - MGM
Paul Muni - MGM
Eleanor Powell - MGM
William Powell - MGM
George Raft - Paramount
Barbara Stanwyck - MGM
Robert Taylor - MGM
Spencer Tracy - MGM
Loretta Young - 20th Century-Fox