What do you mean by “famous?” My first thought was famous within the fitness industry, which would in most cases be fitness educators of well-known programs. And in order to teach others those programs and be a CEC provider, yes, they’re going to be certified by ACE, AFAA or both.
As soon as you define fame to mean known outside the industry, there are “fitness celebrities” who have ACE certification plus much much more. Sadly, there are also a lot of people who are well known but don’t actually know all that much.
There was a recent article posted on this site called “certification by selfie,” implying that these days, looking good and being adept at social media can get you clients, regardless of whether you can actually teach others or if your methods are safe, effective, and sustainable.
Why do you ask?
If you are looking for someone with whom you can work there are many well trained, experienced coaches and it should not be hard to find someone with whom you can work well. You could look on the ACE site for a list of those near you.
If you need to get quotes for an article or blog you might look to people who have written well on the topic and connect to them.
Just remember fame is not the touchstone of ability or work ethic or knowledge. I am sure we could all name a number of people famous within modern media not for their skills or knowledge.