Do any of you have experience, or can anyone suggest a source of information on the legal ramifications (if any) on using the name of a popular public figure in my book?

I have completed a novel in which the MC has a (harmless) fixation on a famous media personality Ė letís say itís Oprah Ė and although the story itself has nothing to do with Oprah, the MCís thoughts and actions are driven by her admiration of this person who has had a tremendous positive influence on her.

Is it legal to use a real personís name, if it is someone that has purposely created a public persona and is so widely known? It could be Madonna, or Steven Colbert, or President Obama for that matter. I believe my question is the same for any public figure.

If so, would there be some restrictions on what you could write?

Is there a previous thread on this, because I couldnít find anything?

Thanks in advance for any guidance you can provide.