On a resume, one of the worst things you can do is name drop people you don't know well -- especially celebs! While it’s fine (although not necessary) to list the name of the agent you worked for at CAA, it’s inappropriate to list his client roster. If you want to highlight that the talent you were interacting with was top tier, simply write “roster of A-list directors.” You also shouldn't name drop a company's top executive if you didn't assist him directly. For example, don't throw Ron Howard's name around if you are the assistant to the VP of Development at Imagine Entertainment -- referencing him makes you look like an amateurish fanboy who can't believe he got so close to someone so powerful. Keep in mind that listing a person’s name on your resume is the equivalent of an endorsement by that person. But just because your boss repped a notable writer or actor doesn't mean that this person would go to bat for you. If you're close enough to a Hollywood power player that actually would go out of their way to help you, they probably passed along your resume in the first place, making the name drop redundant.
Secondly, you shouldn't name drop anyone who isn't well-known on your resume. It's much more useful to a hiring manager to see "Assistant to VP of Production" as a job title than "Assistant to Jane Doe." Sure, maybe someone who knows your boss will see your resume, but if that person has the type of relationship with your boss that you could actually take advantage of, you can assume he will know the name of the company and can connect the dots on his own. [Note: This rule does not apply to personal assistant positions (although make sure the person you are assisting is okay with you listing his name -- you don't want to compromise his privacy).]
Ultimately, your skills and experience should speak for themselves. If you know someone important that can help you will the job search, they will be more useful to you behind the scenes making phone calls and passing your resume along. There’s no need to fluff your feathers by including names of celebrities or top-tier executives in your job applications.