The Romans called it “Sol” and the Greeks “Helios” but our “Sun” is actually without a proper name now. All other suns we see in th enight sky and we know of are given names such as Polaris (or Great Bear) and Betelgeuse, but our sun is simply called “Sun”. It does have an officlal symbol though – a circle with a dot in the middle.
You have your answer from my learned friends above, but did you know that the sun is the perfect size, perfect age, perfect distance, perfect temperature and perfect brightness for life to exist on a planet like Earth. So maybe the sun should be called “perfect”??