Question

Using athlete michael jordan in a nike commercial or beyoncé in a pepsi ad rather than unknown actors is an example of a very popular form of advertising today—the use of

Answer 1

It's the use of endorsement.
The endorsement is a type of advertising that leverage on the popularity or influence of a certain individual in order to publicize thier product/service.
Companies often offer endorsement to people with huge fan base or followers such as famous athletes/celebrities.