Move to United States
In 1973, Eggar moved to the United States, settling in Los Angeles, and appeared first in television, guest-starring in episodes of Starsky & Hutch, Hart to Hart and Columbo. She would go on to star in a number of horror films, including A Name for Evil (1973) and Demonoid (1981).
During this period, Eggar also appeared in two British-Canadian co-productions, Welcome to Blood City, an early "virtual-reality" thriller directed by Peter Sasdy in which she plays opposite Jack Palance and Keir Dullea, and The Uncanny, a horror movie directed by Denis Héroux.
Eggar was also in the Canadian movie Why Shoot the Teacher?, a dramatic comedy filmed in Alberta by Silvio Narizzano that went on to be the most successful Canadian movie that year. But it is another Canadian movie that was to become one of Samantha's best known films, David Cronenberg's cult sci-fi film The Brood (1979).
In 1980, she filmed the Canadian slasher film Curtains, released in 1983.
She also appeared as Maggie Gioberti in "The Vintage Years", the pilot for the drama Falcon Crest, but was replaced by Susan Sullivan when the series went into production. She appeared twice on The Love Boat in 1979 and 1981. She appeared in the drama Dark Horse (1992), followed by the superhero film The Phantom (1996). In 1997, she provided the voice of Hera in Disney's animated film Hercules; she also supplied the voice for the subsequent television series. Eggar also had a role in the sci-fi thriller The Astronaut's Wife (1999), which starred Johnny Depp.
Eggar appeared as the wife of Captain Jean-Luc Picard's brother Robert on the television series Star Trek: The Next Generation, and as Sarah Templeton, the wife of Speaker of the House Nathan Templeton (Donald Sutherland), on the short-lived television series Commander in Chief, which starred Geena Davis. In the year 2000, she had a brief run as Charlotte Devane in the American soap opera All My Children. In 2002, she provided the voice of M in the video game James Bond 007: Nightfire. In 2004, she appeared in the first season of Cold Case, episode 14 ("The Boy in the Box") as Sister Vivian. In 2009, she played the mother of Jack and Becky Gallagher in season 1, episode 11 ("Lines in the Sand") of the Fox television series Mental.