Several actors came and went throughout the seven seasons of Star Trek: The Next Generation, but these four regulars quit the show of their own accord. Beginning in 1987, TNG followed the adventures of Captain Jean-Luc Picard (Patrick Stewart) and his crew on the USS Enterprise-D. While the first season established TNG’s main characters, the quality of the episodes was inconsistent as the show struggled to figure out what it wanted to be. Part of this inconsistency was caused by the notoriously chaotic writing team, as writers came and went with surprising regularity.

Star Trek: The Next Generation‘s early writer’s room chaos was part of the reason why Denise Crosby, who played Security Chief Lt. Tasha Yar, left during TNG’s first season. TNG season 2 introduced Diana Muldaur’s Dr. Katherine Pulaski to replace Gates McFadden’s Dr. Beverly Crusher, who had been fired by TNG’s then-showrunner Maurice Hurley. Dr. Pulaski would prove to be an unpopular character, and Muldaur left the series at the end of season 2. Wil Wheaton became the third actor to quit Star Trek: The Next Generation as his character Wesley Crusher left to attend Starfleet Academy. One of the more popular additions to the cast in TNG‘s later seasons, Michelle Forbes’ Ensign Ro Laren, almost played a much larger role in the Star Trek franchise, but the actress chose another path.

Star Trek: The Next Generation Cast & Character Guide

Star Trek: The Next Generation has one of the most beloved cast of characters in all of science fiction. Here are the major characters of the classic.

4 Denise Crosby as Lt. Tasha Yar

TNG’s doomed security chief.

Tasha Yar’s death in Star Trek: The Next Generation season 1 was notable as the first time one of Star Trek’s main cast members had been permanently killed off. Denise Crosby decided to leave the show before the first season concluded, although it was Star Trek creator Gene Roddenberry who decided to kill off her character. In a 2012 interview with StarTrek.com, Crosby discussed why she left saying: “I didn’t want to spend the next six years going ‘Aye, aye, captain,’ and standing there, in the same uniform, in the same position on the bridge.”

It was true that Tasha Yar was underused as a character throughout TNG season 1. As the Security Chief, she should have been the first line of defense against any enemies, but Tasha was often sidelined while other characters were given the main storylines. It took a couple of seasons for many of the characters to truly find their footing, and it would have been interesting to see Yar grow and develop as a character. Still, Crosby did get to return later as different versions of Tasha Yar in TNG season 3’s “Yesterday’s Enterprise,” as well as the series finale, “All Good Things….” She also appeared in two TNG season 5 episodes as Sela, the Romulan daughter of the Yar from “Yesterday’s Enterprise.”

3 Diana Muldaur as Dr. Katherine Pulaski

TNG’s prickly and unpopular doctor.

Before Star Trek: The Next Generation season 2, Gates McFadden was fired from the show by head writer Maurice Hurley. With Dr. Crusher gone, the USS Enterprise-D needed a new doctor and Diana Muldaur was brought in as Dr. Katherine Pulaski. Although TNG season 2 showed a marked improvement over the show’s first season, Dr. Pulaski wasn’t as popular as Dr. Crusher had been. Pulaski’s personality channeled that of Dr. Leonard McCoy (DeForest Kelley) from Star Trek: The Original Series, but she never quite found her place among the rest of the Enterprise-D crew.

Although Muldaur has not revealed much about her departure from the show, she had only signed a contract to appear in one season. In a recent interview in Star Trek Explorer issue #9, Muldaur revealed a bit more about her exit from TNG, saying: “I left the show because the year was up, simple as that, under my own power.” It seems Muldaur had decided to leave the show regardless of anything going on behind the scenes or the lukewarm reception to her character. Muldaur has stated in other interviews that she never planned to stay on TNG for an extended period, and her portrayal of Pulaski helped the actress land a role on L.A. Law.

2 Wil Wheaton as Ensign Wesley Crusher

TNG’s boy genius.

Fresh off of the success of Stand By Me, the young Wil Wheaton made his Star Trek debut in TNG’s premiere episode as Wesley Crusher. The son of Dr. Beverly Crusher, Wesley was a child prodigy who loved everything about serving on a starship. Unfortunately, Wesley had a tendency to find solutions to problems that stumped even the most experienced Starfleet officers, which didn’t exactly endear him to fans. TNG’s writers struggle to write for Wesley as a character, and Wheaton was having his own troubles behind the scenes.

Wil Wheaton has made no secret about the emotional abuse he suffered at the hands of his parents, and it was partly their manipulation that led him to quit TNG. Only eighteen when he left TNG in the show’s fourth season, Wheaton feared losing out on bigger acting opportunities by staying. Wheaton had already had to turn down offers due to his commitment to TNG, and, at the time, he (and his parents) dreamed of bigger things than Star Trek. Wheaton returned to play Wesley in four more episodes of TNG, as well as a brief appearance in Star Trek: Nemesis.

1 Michelle Forbes as Ensign Ro Laren

TNG’s first Bajoran Starfleet officer.

Introduced in Star Trek: The Next Generation season 5, episode 3, “Ensign Ro,” Michelle Forbes’ Ensign Ro Laren proved to be one of TNG’s most popular secondary characters. The Bajoran Starfleet officer appeared in eight episodes of TNG, including the penultimate episode of the series, “Preemptive Strike,” which saw her betray Captain Picard to join the rebel Maquis. At the time, this put an end to Ro’s Star Trek story, but the Bajoran Starfleet officer was originally meant to join the main cast of Star Trek: Deep Space Nine.

Although Forbes was offered the role of Commander Benjamin Sisko’s (Avery Brooks) first officer on DS9, she turned it down and Michelle Forbes left the Star Trek franchise. With 20+ episode seasons, being a main cast member on a Trek show at the time was a major commitment, and Forbes wanted more variety in her career. Forbes’ decision ended up working out, as she went on to appear in a wide range of movies and television shows, and DS9 cast Nana Visitor as Major Kira Nerys. Even though Denise Crosby, Diana Muldaur, Wil Wheaton, and Michelle Forbes cut their Star Trek careers short, they remain significant and beloved members of the Star Trek family.