Denise Crosby, the granddaughter of famous singer Bing Crosby, is well known for playing Lt. Tasha Yar, the Chief Security Officer onboard the USS Enterprise in the first season of Star Trek: The Next Generation. However, the actor was set to play an entirely different character -- the ship's telepathic, empath counselor, Deanna Troi.

A memo written by Paramount's Head of Network TV in 1987 details the various talent considered for the roles of the Enterprise crew, with Lianne Langland, Julia Nickson, Rosalind Chao (who played Keiko O'Brien in The Next Generation and its spinoff Deep Space Nine), Leah Ayers and Bunty Bailey all up for the role of the ship's Chief Security Officer, while Crosby was the only actor named as reading for the part of Troi. Things changed when Marina Sirtis tried out for the role of Yar, then known as Macha Hernandez, a character inspired by the tough-as-nails space Marine Vasquez from James Cameron's Aliens.

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Tasha Yar and Worf appear shocked while on board the Enterprise

According to the Star Trek: The Next Generation Companion Guide, the background stories on Troi and Yar came to be intertwined with the actors who would play the roles. Believing that she possessed an exotic beauty that was better suited for the ship's counselor than Security Chief, Gene Roddenberry, the creator of Star Trek, switched the roles. Macha Hernandez became Tasha Yar and was given a Ukrainian background to match Crosby's blonde hair, and Sirtis became the half-Betazoid counselor with a human father.

Once The Next Generation began airing, it took some time for the show to find its footing and the cast to settle into their roles. Unfortunately, this never seemed to happen for Crosby, who became dissatisfied with Yar's treatment and lack of substance and proper development. She requested to leave The Next Generation early to pursue a film career and became the first major character in the franchise to be permanently killed off. Crosby later returned to Star Trek to play an alternate timeline version of her character, the villainous blonde Romulan Sela, the daughter of Yar's alternate version.

Star Trek: The Next Generation stars Patrick Stewart, Jonathan Frakes, LeVar Burton, Denise Crosby, Michael Dorn, Gates McFadden, Marina Sirtis, Brent Spiner, Wil Wheaton and more. The show is available to stream on Netflix, Paramount+ and other platforms.

Keep Reading: Star Trek: The Next Generation - Why Denise Crosby's Tasha Yar Left After Season 1