Euphemia Potter (née Moon) (died c. 1979) was a pure-blood witch. She was married to Fleamont Potter, with whom she had one son, James Potter I, thus making her the paternal grandmother of the famous Harry Potter, and the great-grandmother of James Sirius, Albus Severus, and Lily Luna Potter.
Little is known about Euphemia's early life other than she was born it the Moon Family, a ancient and influential pure-blooded family. She and her husband Fleamont lived a comfortable life due to his wealth. They had trouble having children and eventually gave up the hope of ever having a son or daughter of their own. However, in 1959, to the couple's shock and delight, Euphemia discovered she was pregnant, and gave birth to a son, James, on 27 March 1960.Due to her late-in-life pregnancy, James was an only child, and was doted on quite a lot.
When James's best friend, Sirius Black, ran away from home at age sixteen, he found refuge in the Potter household. Euphemia and her husband came to regard Sirius as something of a second son. After Sirius moved into his own flat, he kept in touch with the Potters, and was always welcome to have lunch with them on Sundays.
Advancing in age, both Euphemia and her husband Fleamont succumbed to Dragon Pox shortly after the marriage of their son James to Lily Evans, in 1978-1979, dying within days of each other. Euphemia never got a chance to meet her grandson, who would only be born after his grandparents' deaths, on 31 July, 1980, but she was probably among the relatives who Harry saw when he looked into the Mirror of Erised in 1991.
Euphemia is a Greek name. "Eu" means good and "phemi" means to speak.