Alexis Carrington Colby (née Morell, formerly Dexter and Rowan) is a fictional character on the American TV series Dynasty. She is the ex-wife of Blake Carrington (John Forsythe) and her schemes cause one problem after another for him and their children.

The role was originated by Joan Collins in the first episode of the show's second season in 1981, though the character appeared briefly in the first-season finale, non-speaking and face unseen. Collins remained on the show until the finale in 1989, and then returned as Alexis for the 1991 miniseries Dynasty: The Reunion. The character appeared later in the first season of the 2017 Dynasty reboot series, portrayed by Nicollette Sheridan from the sixteenth episode of the first season to the fifteenth episode of the second season. Actress Amy Sutherland played a bandaged, non-speaking Alexis in the sixteenth and seventeenth episodes of the second season. Elizabeth Gillies, who stars as Alexis's daughter Fallon, played the role of Alexis after Sheridan's departure for three episodes near the end of the second season. The role was recast with Elaine Hendrix for season three.

Alexis' schemes to destroy ex-husband Blake, undermine his marriage to Krystle (Linda Evans), and control her children drive much of the action over the series' run. Passionate, shrewd, and vengeful, Alexis loves her children fiercely and will do anything to protect them, but she often ignores their own needs and desires in place of what she thinks is best. Alexis marries three additional times, to Cecil Colby (Lloyd Bochner), Dex Dexter (Michael Nader), and Sean Rowan (James Healey). She is widowed twice, first by Cecil and then by fourth husband Sean, prompting Alexis' cousin Sable to remark that with Alexis "death is always a simpler solution than divorce." Her third marriage (to Dex) ends in divorce after Alexis catches him in bed with her adult daughter Amanda (Catherine Oxenberg). The name Alexis uses the most consistently over the course of the series is Alexis Colby, though her marriage to Cecil Colby is her shortest. Alexis is romantically linked to a number of men over the years, including oilman Rashid Ahmed (John Saxon); tennis pro (and Krystle's first husband) Mark Jennings (Geoffrey Scott); King Galen of Moldavia (Joel Fabiani); shipping tycoon Zach Powers (Ricardo Montalbán); Congressman Neal McVane (Paul Burke); Blake's brother Ben Carrington (Christopher Cazenove); Dirk Maurier (Jon Cypher) and his nephew Gavin Maurier (Neil Dickson); Cecil's brother Jason Colby (Charlton Heston); and even a near-reconciliation with an amnesiac Blake.

TV Guide named Alexis No. 7 in its 2013 list of "The 60 Nastiest Villains of All Time", and in 2016 Rolling Stone ranked her No. 27 of its "40 Greatest TV Villains of All Time". In 2015, executive producer Lee Daniels noted that Taraji P. Henson's character Cookie Lyon in his TV series Empire was partially based on Alexis.

In the first-season finale episode, "The Testimony", Blake Carrington is on trial for murder, and a female mystery witness in a large hat and veil appears. Writers Eileen and Robert Mason Pollock, brought in for season two, were told by series creators Richard and Esther Shapiro that the character would be Blake's ex-wife Madeline, who would be played by Sophia Loren for four to six episodes. The Pollocks renamed her Alexis, told executive producer Aaron Spelling that Loren was not right for the part, and warned him that "If you get rid of this character in four episodes, you are throwing away hundreds of millions of dollars." Joan Collins said in 2018 that in addition to Loren, producers pursued Elizabeth Taylor and Jessica Walter. According to Collins, "They were waiting for Jessica until the very last minute, so they didn't cast me until two weeks before we started shooting."

Esther Shapiro later said that the character of Alexis was based on the Roman empress Livia as characterized in the 1934 novel I, Claudius. Of creating the character, Collins said in 2018, "I was basing her on all the businessmen I knew who were heartless, really. The other part of her brain, the glamorous part with the over-the-top clothes, I based on one of my best friends called Cappy Badrutt. She was extremely glamorous, and unfortunately very miserable. But I don't think Alexis was miserable. I think she enjoyed her life and lived it to the fullest." She had previously singled out Donald Trump to be one inspiration for the character in a 2013 PBS interview.

Shapiro said in 1985 that she and costume designer Nolan Miller "had the same vision" for Alexis: Joan Crawford. She added, "Nolan had designed for Crawford, and he told me that she had a photo index of every outfit she owned. Everything was coordinated: Each dress had its own particular hat, purse, gloves, shoes, and it never varied. Joan Crawford didn't mix and match. We decided to take it one step further: Alexis would never wear the same thing twice. In fact, no one on Dynasty would."

The character of Alexis is a foil for "good girl" Krystle (Linda Evans), with an opposing moral stature and attitude. Described as "scheming, conniving, and ruthless", Alexis was often called a "superbitch" and the "quintessential character you love to hate" by critics. Vernon Scott of the Sun-Sentinel called the character "the scourge of Dynasty".