(written from a Production point of view)
Bujold was the first choice of the producers of Star Trek: Voyager to play Captain Nicole Janeway. She quit after a day and a half of shooting, with the public reason being she was unaccustomed to the hectic pace of television filming. (See: Bujold as Captain Nicole Janeway) Other rumored reasons included dissatisfaction with her performance on the part of the producers and dissatisfaction with the character on the part of Bujold. As Rick Berman politely put it in the October 8-14, 1994 issue of TV Guide: "It was immediately obvious it was not a good fit." The producers subsequently hired TV veteran Kate Mulgrew, and changed the captain's first name from Nicole to Kathryn on Mulgrew's advice.
In 2006, Rick Berman shed more light on Bujold's departure from the series. "This was a woman, who in no way, was going to be able to deal with the rigors of episodic television." He tried telling his feeling about Bujold to Voyager co-creators Jeri Taylor and Michael Piller, who assured Berman that it was not going to be a problem. Berman recounted some of Bujold's problems on the set of "Caretaker", from her having trouble with memorizing seven pages of dialogue a day, to wanting to not have her hair touched up by hair dressers, to not wanting to have to work with a director she did not know. Berman also recalled that after working on the set during the second day of shooting, Bujold went to her trailer in tears. Later, both "Caretaker" director Winrich Kolbe and Berman met with her there, and asked her to go home. 
In the 1960s, Bujold starred in international art films such as La guerre est finie (The War Is Over, 1966), Le roi de coeur (King of Hearts, 1966), and Anne of the Thousand Days (1969), in which she played Anne Boleyn opposite Richard Burton as Henry VIII; for that role, she was nominated for an Academy Award and won a Golden Globe Award. The latter film also co-starred John Colicos.
From the 1970s, Bujold concentrated more on Hollywood roles, in films such as Earthquake (1974, with George Murdock, Gene Dynarski, Jerry Hardin, and George Sawaya), Swashbuckler (1976, with Sid Haig and directed by James Goldstone), Coma (1978, with Lance LeGault, William Wintersole, Harry Basch and music by Jerry Goldsmith), Tightrope (1984, with Janet MacLachlan), and Dead Ringers (1988, directed by David Cronenberg).
In an interview in 2017, Robert Beltran expressed in an interview that Bujold was one of the reasons he wanted to be on Star Trek: Voyager, as he loved her as an actress. He felt that it would be fun and challenging to do scenes together as her first officer, but ultimately felt once he started working together with Kate Mulgrew that she was a great choice and very capable.