Sabella "Sable" Scott Colby is a fictional character from the ABC television series Dynasty and its spin-off The Colbys, both created by Richard and Esther Shapiro. Portrayed by Stephanie Beacham, the character was introduced on Dynasty in the November 1985 two-part episode "The Titans" as the socialite wife of wealthy California CEO Jason Colby (Charlton Heston). Beacham was subsequently a series regular on The Colbys for two seasons from 1985 to 1987. She reappeared as Sable on Dynasty for its ninth and final season from 1988 to 1989.

In March 1985, ABC announced that its rumored Dynasty spin-off, The Colbys, had been greenlighted, to debut the following season. Charlton Heston was cast as patriarch Jason Colby in July 1985, and it was reported that The Colbys' versions of Dynasty rivals Krystle Carrington (Linda Evans) and Alexis Colby (Joan Collins) would be named Anthea (later changed to Francesca) and Sable. Faye Dunaway, Angie Dickinson, Elizabeth Ashley, and Diana Rigg all turned down the role of Jason's wife Sable. Producers started auditioning British actresses to play one of the sisters as the equivalent of Collins's Alexis. According to Kate O'Mara, she and Stephanie Beacham were the final two choices to play Sable, but O'Mara was already under contract with a stage play in London. O'Mara later played Caress Morell, the sister of Collins' character Alexis, on Dynasty. In August 1985, producers cast Beacham, "a household name" in the UK who had starred in the title role of the ITV drama Connie.

On vacation after playing a ruthless businesswoman on Connie, Beacham almost passed on the request that she return to London to screen test for The Colbys. She was compelled to return when her housesitter locked the keys in her home. Beacham tested on a Friday, was flown to Los Angeles a week later, and was in wardrobe the next day. She noted of her audition, "I said whatever rubbish I could remember and camped it up". Beacham later explained that her main reason for doing The Colbys was her pay, which was an estimated $20,000 per episode. Beacham said that she and Heston were "a very lovely team", and that "What was really flattering actually was that the crew always used to gather around to watch the first run-through of our scenes, not just because they had to." Beacham is completely deaf in her right ear and has only 70 percent hearing in her left, and she compensates by positioning herself to the right of other actors in as many scenes as possible.

Beacham debuted as Sable in the Dynasty episodes "The Titans - Part 1" and "The Titans - Part 2", which aired back-to-back on November 13, 1985. She subsequently appeared as a series regular on The Colbys, which ran for two seasons from November 20, 1985, to March 26, 1987. Beacham later played Sable in the ninth and final season of Dynasty from 1988 to 1989. Sable did not appear in the 1991 miniseries Dynasty: The Reunion.

Jasper Rees of The Telegraph wrote in 2016 that "Stephanie Beacham will forever be known as blow-dried, shoulder-padded vamp Sable Colby". Barbara Holsopple of The Pittsburgh Press called Sable "scheming" and "smarmy", noting that Jason's wife is ruffled by his sister Constance Colby's (Barbara Stanwyck) bestowal of her company shares on her nephew Jeff (John James) rather than to Jason and Sable's three children. David Wallace of People described Sable as "wily", and recounted how Sable deals with Constance by first trying to have her declared incompetent and then by sabotaging her horse's saddle. Dynasty co-creator Esther Shapiro said of Beacham, "We loved her patrician quality. Despite Sable's seamy side, you understand why a major tycoon would stay married to her." Wallace dubbed Beacham "the show's real fire", and wrote that she "might just be the one to show Joan Collins the real meaning of she-deviltry." In February 1986, Beacham said that a confrontation between Sable and her cousin Alexis (Collins) might be "jolly good fun." Beacham commented in 2012 that she and Collins "felt we represented the Eighties."

Beacham said of Sable, "When she gets cross, frightful things can happen...I've allowed Sable to get more and more neurotic...she's such a terror." Beacham agreed it could be a challenge playing someone with so much emotion, but called Sable "a nearly three-dimensional human being".

The Colbys of Los Angeles come to Denver to celebrate a new business venture with oil tycoon Blake Carrington (John Forsythe) in the 1985 Dynasty episodes "The Titans - Parts 1 and 2". Sable is married to mogul Jason Colby, and the mother of their three children: Miles (Maxwell Caulfield), Monica (Tracy Scoggins), and Bliss (Claire Yarlett).

In the series premiere, "The Celebration", the Colbys return to Los Angeles and Sable is upset that Jason's sister Constance has given her shares to her nephew Jeff rather than Sable and Jason's three children. A dismissive Jason tells Sable to stay out of it, but she makes a failed attempt to convince Constance that she has made a mistake. Sable is getting worried that no one has heard from Miles, and also tells Monica that it is unlikely Jason will ever treat her like he would a man. In "Conspiracy of Silence", the Colbys are surprised when Miles comes home married to Randall, who they now know is an amnesiac Fallon Carrington (Emma Samms). Sable is delighted that her son has married an heiress. She is reunited with her estranged sister Francesca (Katharine Ross), Jeff's mother with Jason's deceased brother Philip, but makes it clear she hopes Frankie will not stay in town long. Hoping to tie Fallon to Miles, Sable suggests to Fallon that she have a baby as soon as possible in "Moment of Truth". Sable accuses Frankie of conspiring with Constance to benefit Jeff. Frankie intends to leave town, but is convinced to stay by Jason, with whom she had an affair many years ago. Sable comes across Jason's medical report and is shocked to learn that he is dying, unaware that his doctor has told him the diagnosis was a mistake. Sable apologizes to Frankie in "Family Album", hoping she will talk Constance about the shares she gave Jeff. Sable is told that the only way to reverse Constance's decision is to have her declared incompetent. When Constance dismisses Sable a final time, Sable goes to Jason with false concern about Constance's mental state. Sable is sure that Zach's interest in her is only a means to get to Jason, but she begins to soften to him. Sable continues her plan to make Constance appear senile in "Shadow of the Past". Sable loosens Constance's saddle, but is horrified when Frankie takes the horse and is almost injured. Constance, however, starts doubting herself.