Denise Crosby left Star Trek: The Next Generation before season one of the series ended.
Denise Crosby portrayed Lt. Tasha Yar, the Enterprise’s chief of security on Star Trek: The Next Generation for twenty-two first season episodes before her character was killed off in “Skin of Evil,” as Crosby wanted to leave the series. In fact, Crosby has confirmed in previous interviews that she couldn’t wait to get off the show, but she returned in season three’s “Yesterday’s Enterprise” for a proper sendoff for the lieutenant.
Seasons four, five, and seven saw Crosby return as a different character, Sela, Tasha Yar’s daughter, and now it looks like she’ll be appearing in the third season of Star Trek: Picard. According to Syfy.com, she will reportedly be returning to the character of Tasha Yar. With most of the characters of Star Trek: The Next Generation returning, it’s possible we’ll see Crosby in a flashback episode or a dream sequence. Bringing her back as a living, breathing character would be strange and not altogether beneficial, in my opinion.
Denise Crosby did not have a fully fleshed out character on Star Trek: The Next Generation.
That was Crosby’s problem with Lt. Tasha Yar. There was no depth to the character. Crosby has said that she was scared of spending six years in the same uniform, in the same position on the bridge, saying “aye, aye, captain.” Even all this time later, she still contends that she made the right decision to leave the series, but that hasn’t stopped her from parlaying her brief time on Star Trek into additional guest spots and appearances at conventions.
She was a part of Star Trek, but the character of Lt. Tasha Yar contributed so little to the series that a return might come across as superfluous on Star Trek: Picard. So it will be interesting to see if and how this character will be a contribution and not a simple cameo.