Star Wars and other movies have toys based on the characters. Do the actors get extra pay when the toys sell or is that all included in the contract they sign? I assume they cannot endorse the toys on their own.
Sports people get extra money to endorse shoes, jerseys , equipment, etc. so that’s a similar situation . And those deals have been around for a long time.
I read that when DVDs of TV shows started to sell at first actors did not get any extra money for those sales. In fact the Seinfeld actors did not want to promote the DVDs since they were not getting paid. They signed a deal to get paid so they agreed to promote them.