Who was don goon of Tae Kwon Do?

Answer 1

It is possible that you are referring to Dangun Wanggeom (aka: Tan Gun or Tangun) who was the legendary founder of Joseon (later referred to as "Gojosen" or "Old Joseon when the final Yi Dynasty was called Joseon), which was the first kingdom established near the top of the Korean peninsula.

Dangun was not directly involved in Taekwondo, but was a legendary figure of Korean history, therefore his name was used by Korean Army General, one of Taekwondo's early pioneers, as the name of the second student practice form in his Chang Hon system that he implemented in his Oh Do Kwan ("Gym of My Way") for the Korean military, and later in his ITF (International Taekwondo Federation).