During the Golden Age of Hollywood, many companies tried to latch onto the aura of movie star glamour, and arguably no brand did it better than Lux soap. Of course, for many years, "Lux Radio Theater," featuring film stars in movie adaptations, was one of radio's top-rated shows, and Carole Lombard made several appearances on the program (http://community.livejournal.com/carole_and_co/3807.html).
But even before that, Lombard -- like many leading actresses of her time -- had ties to the soap. In late 1934, Lux had an offer where it gave away 33 portraits of top film stars, both male and female. Below is an envelope sent to retailers:
The portraits, which included a facsimile autograph, measured 9" x 12" and were printed on light cardboard stock. Here's what Lombard's looked like:
For more on this premium, including other portraits and a partial checklist, go to http://www.things-and-other-stuff.com/movies/ephemera/1934-lux.htm.
The following July, Carole appeared in a two-page print ad for Lux in Photoplay, one of the top fan magazines:
Here are two more Lombard Lux ads:
Most movie stars who made such ads received a nominal fee (and, of course, some soap) for their efforts -- but the bulk of the money was made by the studios, which invariably plugged the star's upcoming film in the ad.
As for Lux soap. it hasn't been commercially produced in the U.S. for some time now, but it's still a popular brand in many other countries. One of them is India, where many "Bollywood" stars endorse the soap in ads.