Well, besides being the first guy to set foot on the moon....
Neil Armstrong had an extensive career as a United States military pilot. He flew multiple types of aircraft as an American military pilot. He was an astronaut in the United States Space program. He had his start with the Gemini projects and culminated his astronaut days with the flight that landed him on the moon, Apollo 11. He was an aerospace engineer and also served as a university professor.
But his biggest claim to fame is when he stepped off the lunar lander on July 20, 1969, onto the surface of the moon. America had been beaten by the Soviet Union (Russia) at every twist and turn, as the two super powers struggled against each other to gain an advantage. The Russians were first in everything involved in the Great Space Race. America gained the advantage when Armstrong and company successfully landed on the moon. Armstrong is best remembered for his now famous quotation, as he stepped onto the lunar landscape: "That's one small step for man, one giant leap for mankind".