Celebrity Space

I have been pondering what it is that constitutes a 'celebrity' lately, and while I haven't exactly answered the question myself, it did get me to thinking about the extent to which someone is internationally famous.  During my lunch hour I sketched the following Venn diagram about celebrities in the U.K., U.S., and Australia (I couldn't figure out how to handle Canadians just yet) based on their professions.  Notice that I left off celebrities from the arts, politics, and news of the weird for now (click here for a bigger image).
According to my diagram, there are relatively few athletes who become international celebrities, whereas musicians and movie stars are likely to have a bigger world impact. I also couldn't think of any instances where someone is a celebrity in Australia and the U.S., but not one in the U.K., whereas there are many uniquely popular in the U.K. and Australia.  But what do you think?