Do your homework, check to see if they have their name registered as a trademark using the intellectual property website. Think about what your expected return on your investment will be and how you will capitalise on your investment. If you are using the actors name to directly profit from the domain you will likely loose the domain if challenged.
Research the actor in question and see how likely this is to happen, if it is very likely to happen then you could always profit indirectly by redirecting the domain to a relevant money site if the actor in question is very well known and you are likely to have type-in traffic.
Look online by searching "domain registration tips" and researching the subject thoroughly.
Good luck,
8lack.