Euphemia ('Effie') Chalmers Gray (1828 - 1897) was the wife of the critic John Ruskin but later left her husband to marry his protege, the Pre-Raphaelite painter John Everett Millais. This famous Victorian "love triangle" has been dramatised in several plays and an opera.

Effie was born in Perth, Scotland and lived in Bowerswell, the house where Ruskin's grandfather had committed suicide. Her family knew Ruskin's father, who encouraged a match between them. In 1842 Ruskin wrote the fantasy novel The King of the Golden River for Effie. After their marriage they travelled to Venice where Ruskin was researching his book The Stones of Venice. However, their different temperaments soon caused problems, with Effie coming to feel oppressed by Ruskin's dogmatic personality. When she met Millais five years later Effie was still a virgin, as Ruskin had persistently put off consummating the marriage. She modelled for Millais' painting The Order of Release, in which she was depicted as the loyal wife of a Scottish rebel who has secured his release from prison. She then became close to Millais when he accompanied the couple on a trip to Scotland in order to paint Ruskin's portrait according to the critic's artistic principles. During this time spent in Brig o'Turk in the Trossachs they fell in love. Effie left Ruskin and she filed for an annulment, causing a major public scandal. In 1855, after her marriage to Ruskin was annulled, Effie and John Millais married. During the marriage she bore Millais eight children. She also modelled for a number of his works, notably Peace Concluded (1856), which idealises her as an icon of beauty and fertility.

When Ruskin later became sought to become engaged to a teenage girl, Rose la Touche, Rose's parents were concerned. They wrote to Effie, who replied by describing Ruskin as an oppressive husband. There is no reason to doubt Effie's sincerity, but her intervention helped to break up the engagement, probably contributing to Ruskin's later mental breakdown.

After his marriage, Millais began to paint in a broader style, which Ruskin condemned as a "catastrophe". Marriage had given him a large family to support, and it is claimed that Effie encouraged him to churn out popular works for financial gain and to maintain her busy social life. However, there is no evidence that Effie consciously pressured him to do so, though she was an effective manager of his career and often collaborated with him in choosing subjects. Effie's journal indicates her high regard for her husband's art, and his works are still recognisably Pre-Raphaelite in style several years after his marriage. However, Millais eventually abandoned the Pre-Raphaelite obsession with detail and began to paint in a looser style which produced more paintings for the time and effort. Many were inspired by his family life with Effie, often using his children and grandchildren as models.

The annulment barred Effie from some social functions. She was not allowed in the presence of the queen, so if the queen was present at a party then Effie was not invited. Prior to the annulment, she had been socially very active and this really bothered her. Eventually, when Millais was dying, the queen relented, allowing Effie to attend a royal function.

Effie died a few months after her husband. She is buried in Kinnoull churchyard, Perth, which is depicted in Millais's painting The Vale of Rest.

Effie's marriage to Ruskin and her romance with Millais have been dramatised on many occasions:

*The Love of John Ruskin (1912) a silent movie about Ruskin, Effie and Millais. *The Passion of John Ruskin (1994), a short film directed by Alex Chappel, starring Mark McKinney (Ruskin), Neve Campbell (Rose la Touche) and Colette Stevenson (Effie). *"Modern Painters" (opera) (1995) an opera about Ruskin, Effie and Millais. *The Countess, (1995) a play written by Gregory Murphy concentrating on the breakdown of the marriage between Ruskin and Effie. *The Order of Release (1998) A radio play by Robin Brooks about Ruskin, Effie and Millais. *The Woman Who Gave Birth to Rabbits (2002), a collection of short stories by Emma Donaghue, contains a story Come, Gentle Night about Ruskin and Effie's wedding night. * Mrs Ruskin (2003), a play by Kim Morrissey about the breakdown of the marriage and Effie's fraught relationship with Ruskin's domineering mother.