Gene Roddenberry was insistent about one part of Khan’s name.
When details for the Star Trek: The Original Series episode “Space Seed” were still underway, the writer who’d pitched the script, Carey Wilber, didn’t have a lot of backstory from the series as it had only been on the air for three weeks. So he was making things up as he went along.
In his script, Khan was actually known as Harold Erickson who was a criminal aboard the Botany Bay. He was supposed to be a blond, Aryan type of character who didn’t have any special abilities. He was just a brute with anger issues. And, according to Gizmodo, It wasn’t until Ricardo Montalban was cast that things began to change. And one of those first changes was the character’s name.
Khan’s name was very important to Gene Roddenberry for a heartfelt reason.
Once Montalban was hired for the role, the name was changed to Sabahl Khan Noonien. Khan didn’t come in until later, but Noonien was one name Gene Roddenberry insisted on because it was part of a search for someone he cared about. He had a Chinese friend in the 1940s who was named Noonien Wang. He and Roddenberry had lost touch over the years, and Roddenberry though that if “Space Seed” aired in China one day, perhaps his friend would hear the full name of Khan Noonien Singh and reach out to the creator of Star Trek.
That didn’t happen in the 1960s which is why Star Trek: The Next Generation’s Lt. Commander Data was created by Dr. Noonien Soong. Roddenberry continued to try to reach his friend. Unfortunately, without the technically we have available at our fingertips today, it was much more difficult to locate people who’d gone missing from our lives. I don’t know if Roddenberry ever reconnected with Noonien Wang, but if not, it certainly wasn’t for lack of trying.