Sheldon Cooper, a fictional character from the popular television series "The Big Bang Theory," is portrayed as a highly intelligent theoretical physicist. Throughout the series, it is mentioned that Sheldon has one PhD. Specifically, he holds a Doctor of Philosophy (PhD) in Theoretical Physics from the California Institute of Technology (Caltech).

Sheldon's character is known for his exceptional intellect, eidetic memory, and deep knowledge in various scientific fields, which sometimes leads to humorous situations where he corrects or outsmarts others. Despite his vast knowledge and expertise, the show consistently refers to him as having a single PhD.

It's worth noting that Sheldon's character often boasts about his academic achievements and intelligence, but the show does not depict him as having multiple PhDs. His single PhD in Theoretical Physics is a central part of his identity and is frequently referenced in the series.

In summary, Sheldon Cooper has one PhD in Theoretical Physics from Caltech, as depicted in "The Big Bang Theory."