DeForest Kelley had been acting long before his iconic role in Star Trek: The Original Series, but the actor remained nameless until he stepped into his role as the world's best space doctor. 

Kelley played the role of Dr. Leonard McCoy, or "Bones" as he's famously known. As the ship's doctor, McCoy was in charge of the health and well-being of Capt. Kirk, Spock and the rest of the crew. He was highly skilled in all kinds of medical procedures for captains and aliens alike. 

In a 1968 interview with Democrat and Chronicle, Kelley said he was thankful for Star Trek because the series helped him make a name for himself in Hollywood and across the country. 

"In the beginning, I was turned down for the series," Kelley said. "Gene Roddenberry (executive producer) wanted me for the role, however, and I was signed for seven of the first 13 episodes. The part wasn't supposed to be much, but I worked very hard, and I was very lucky."

Before Star Trek, Kelley often found himself with small parts in movies, TV series and theater productions, but nothing that gave him the notability that Star Trek did.

According to the interview, Kelley called his work before Star Trek his "naive" years. Here's a few small credits he held in his "naive" years: Lone Ranger (1949), Navy Log (1955), Wanted: Dead or Alive (1958) and 77 Sunset Strip (1958). 

Part of Kelley's reason for not finding fame until Star Trek was due to the fact that he was "too nice." 

"I was a sweet young innocent thing, a pink-cheeked boy from Georgia, when I got into the business back in 1946," Kelley said. "And it has taken me a good many years to realize that nice guys don't mean a damn thing in this business. They get trampled. I wish I had learned that a lot earlier."

Star Trek changed things for the actor. Before his time on the series, Kelley wasn't recognized for the roles he played, he had no notability and he found navigating the industry to be challenging.

As time went on, his Star Trek character became a huge part of the series and the storyline. Who else could stitch up Spock like Dr. McCoy could? Kelley said his hard work and sense of realism about a business in which nice guys finish last helped him succeed in Star Trek. He knew what to look out for and how to avoid it. 

"I put everything I could into it," Kelley said. "But even then I was surprised when I wound up in all the shows. And, as you know, the part has grown into a pretty good level. It's tough to get good exposure on a show with seven regular performers, all hoping to do the same. But we've fairly well worked it out, and each of us seems to have his own set of fans."