Jennifer Lien left Star Trek: Voyager after playing Kes for three seasons, even though Kes was a central and interesting character. Premiering in 1995, Star Trek: Voyager ushered in a new generation of fans after Star Trek: The Next Generation came to an end. In a unique twist, Captain Janeway's (Kate Mulgrew) starship USS Voyager found itself lost in the Delta Quadrant, and embarked on a years-long voyage home. As Kes, Lien was a Star Trek: Voyager series regular. A member of the Ocampa species, Kes possessed telepathic abilities and was romantically involved with Neelix (Ethan Phillips) initially, before breaking off the entanglement in Star Trek: Voyager season 3.
As a young but prodigiously talented member of the Voyager crew, Kes shared certain traits with Wil Wheaton's Wesley Crusher from Star Trek: The Next Generation. Although fans didn't react with quite the same disdain as they did for poor Wes, Kes certainly wasn't the most popular of Star Trek: Voyager's crew. Jennifer Lien's exit came in season 4's "The Gift," after Kes' psychic abilities began spiraling out of control following an encounter with Species 8472. Threatening the very crewmates she had come to love, the Ocampa decides to leave Voyager, evaporating into pure energy and leaving Kes' fate somewhat ambiguous.
Why Jennifer Lien's Kes Left Star Trek: Voyager 
Both viewers and fellow cast members praised Jennifer Lien's acting talent, if not necessarily the development of Kes as a character, and Kes' Star Trek: Voyager exit wasn't without controversy. There were several factors that contributed to Kes's departure from Star Trek: Voyager. Showrunners, Rick Berman and Jeri Taylor have admitted in interviews that the Neelix/Kes romance angle was ill-judged and, despite Lien's best efforts, Voyager had reached a creative dead end with Kes and her unique biology. As an Ocampa, Kes had a tragically short lifespan of only nine years, which limited the story possibilities for her character. In the 2020 book, Star Trek Voyager: A Celebration, authors Ben Robinson and Mark Wright offered another reason for her departure, claiming that Jennifer Lien suffered from mental health issues that began to impact her performance as Kes.
