From pricey perfume to pre-packaged food - having a famous face attached to a product can give companies a big boost.
And the latest trend in celebrity endorsements focuses on working-out and gyms.
Fans of the Bey-hive can now look like the queen. Beyonce's new fashion line, Ivy Park, is for sale.
It's part of a fitness-meets-fashion trend called Athleisure.
Kate Hudson, Brooke Burke, Carrie Underwood and many other celebs have also launched avricewear lines recently.
The point is to make stylish, flattering clothing that can go from the gym to the coffee shop and, in some cases, the office.
The multi-purpose fashion helps widen the base of people buying these brands - meaning more money for apparel companies.
The fitness fashion market has been hotter than ever
According to USA Today, last fiscal year Nike's women's business grey 20 percent.
That's more than twice the rate of growth on the men's side in the same period.
And it's not just Nike.
According to research from the NPD Group, from June 2014 to June 2015 women's fitness apparel outpaced the overall fitness apparel business - growing 9 percent as compared to a little less than 7 percent in the entire industry.
When you are talking about a multi-billion dollar store, those percentages add up, which perhaps means more celebs are wanting to cash in.
What's the Deal: Celebrity fitness fashion
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