Green [née Symonds], Charlotte Byron (1842–1929), promoter of women's education, was born on 12 August 1842 at Berkeley Square, Bristol, the youngest of four surviving children of Dr John Addington Symonds (1807–1871), author and physician, and his wife, Harriet, eldest daughter of James Sykes. Harriet Symonds died of scarlet fever in 1844 and the children were cared for by their maternal aunt, Mary Ann Sykes.

Charlotte Green was educated at home. The atmosphere there was highly cultured, and her development was furthered by her close relationships with her father and her brother, John Addington Symonds the younger. Through them she met Benjamin Jowett, master of Balliol College, Oxford. On 1 July 1871 she married Thomas Hill Green (1836–1882), tutor in philosophy at Balliol and an undergraduate contemporary of her brother. The marriage was childless. She became an influential figure at the college.

Charlotte Green was among the early generation of dons' wives who organized lectures for women in Oxford, succeeding Mary Ward (Mrs Humphry Ward) and Louise Creighton (Mrs Mandell Creighton) in 1873 as secretary to the lectures committee. She was a founding member and the first woman secretary of the Association for Promoting the Education of Women in Oxford, established in 1878 to co-ordinate the teaching of women students. She resigned her secretaryship in 1883 but remained a member of the association's council until its dissolution in 1920.

The Greens were strong supporters of Somerville Hall (later College) which opened in 1879 as a non-denominational hall of residence for women. She arranged tuition for the first students and for many years acted as a chaperone, knitting throughout the mixed lectures to which she accompanied them. She became a member of Somerville council in 1884 and served as vice-president from 1908 to 1926, when she was made a life member. A Greats tutorship established in 1929 was named in her honour. She was great-aunt of a future principal of the college, Janet Vaughan. She also became a member of the first committee of the Society of Home Students (forerunner of St Anne's College) in Oxford, founded in 1893, and continued to serve on the governing body of the society until 1921. She was an intimate friend of its principal, Bertha Johnson. She received the degree of MA honoris causa in June 1921, the year after Oxford opened its degrees to women.

Devastated by the premature death of her husband in March 1882, Charlotte Green was urged by Jowett to remain in Oxford 'where you are so greatly respected and beloved' (E. Abbott and L. Campbell, Life and Letters of Benjamin Jowett, 2, 1897, 194). She was spoken of as a possible principal of both Somerville and Girton colleges, but instead took up nursing in her widowhood, training at the Radcliffe Infirmary, Oxford, for eighteen months and then for six months at the London Hospital. She became a district nurse in Oxford. Jowett was among her patients: she nursed him through his final illness and was reputed to have saved his life in an earlier illness. Much of her work was with the poor and at the Radcliffe Infirmary where her cousin, Horatio Symonds, was a surgeon. In 1893 she was elected to the infirmary's committee of management.

By 1887 Charlotte Green felt that she had been able to do 'what my Husband wanted me to do—to make friends with working people and help them if I could that way' (C. Green to R. L. Nettleship, 24 Dec 1887, R. C. Whiting, ed., Oxford, 1993, 47 n.). Her civic activities included involvement with local schools and membership of the education committee of Oxford city council. She had a particularly close association with the Central School for Girls, and promoted the teaching of domestic science and the care of children regarded as ‘backward’. She was a member of the Women's Local Government Society and, sharing her husband's temperance views, a committee member of the British Women's Temperance Association. Although she had been a signatory in 1889 to Mrs Humphry Ward's protest against women's suffrage, by 1912 she appeared on a suffragist platform and was involved with the National Union of Women Workers.

Charlotte Green died on 4 September 1929 at her home, 56 Woodstock Road, Oxford, and was buried in St Giles's churchyard on 7 September. Her sharp intellect and her continuing interest in higher education made her a popular figure at Somerville College to the end of her life. In her portrait, 'the small, firm mouth and keen grey eyes in the beautiful serene face testify to the capacity for caustic utterance which occasionally varied her tranquil kindness' (V. Brittain, The Women at Oxford, 1960, 42).