After Denise Crosby left Star Trek: The Next Generation, Whoopi Goldberg was ready to take her place.
Denise Crosby played Lt. Tasha Yar, the Enterprise’s Chief of Security, on Star Trek: The Next Generation for less than a season. After Crosby decided to leave the show, there was an opening for the position, and Whoopi Goldberg wanted to be considered for the role.
After Crosby left, Goldberg let the powers-that-be know she was interested, and in “The Center Seat: 55 Years of Star Trek” [via Screenrant], Rick Berman discusses how they were approached and why Goldberg wasn’t given the role.
"“When Denise Crosby decided to leave the show, we got a call from Whoopi Goldberg saying that she wanted to be considered to take Denise’s role of head of security. But Whoopi wasn’t really the head of security type for us. Gene and I sat down and discussed it. “What a great idea to have a bartender?” To build a bar where people could socialize, and who better than Whoopi to play a bartender, who had some kind of strange, never quite explained, past relationship with Picard.”"
Whoopi Goldberg’s role as Guinan gave her a unique access to Captain Picard.
Once Ten Forward was introduced, Goldberg became the bartender who did so much more than tend bar. She was also a close friend of Captain Picard’s, one of his closest confidantes. He even returned to her for advice in Star Trek: Picard’s second season.
Though Berman and Gene Roddenbery didn’t think Goldberg was the head of security type, they certainly saw her as someone who could be counted on to bring wisdom and clarity to the Enterprise’s captain, especially when Picard needed it the most. And for twenty-eight episodes, she shared that wisdom with the ship’s crew, oftentimes leading them to see things they couldn’t see on their own. Guinan was definitely a right fit for Goldberg.