Elsie Violet Locke (née Farrelly; 17 August 1912 – 8 April 2001) was a New Zealand communist writer, historian, and leading activist in the feminism and peace movements. Probably best known for her children's literature, The Oxford Companion to New Zealand Literature said that she "made a remarkable contribution to New Zealand society", for which the University of Canterbury awarded her an honorary D.Litt. in 1987. She was married to Jack Locke, a leading member of the Communist Party.

Locke was the youngest of six children, born Elsie Violet Farrelly in Hamilton, New Zealand on 17 August 1912. She was the daughter of William John Allerton Farrelly (1878–1945) and Ellen Electa Farrelly (née Bryan; 1874–1936). Both of Locke's parents were born in New Zealand, and while only educated to primary level (see Education in New Zealand § Years of schooling), they were both progressive thinkers. William's intelligence was recognised early at school, and he strongly encouraged education for his children, himself being unable to continue his education past Standard Six. Meanwhile, Ellen had been a teenager during the New Zealand women's suffrage movement, and passed on the idea of gender equality to her daughters, as well as teaching them the value of being independent.

Elsie grew up in Waiuku, a small town south of Auckland, where she developed a repugnance towards war at an early age. As a young girl, she witnessed the injuries of World War I veterans first hand — "...when visiting Warkworth I was taken to see a man whose face had been half shot away and who never went off his farm". Though she left Waiuku at a young age, she retained strong ties to the town into her old age, and often returned. Unusually for a Pākehā of her generation, she developed a close relationship with the local iwi in Waiuku, Ngāti Te Ata, and her later research proved vital to their Treaty of Waitangi claim.

While few working class children, particularly girls, went to high school when Locke was young, she continued on to Waiuku District High School, a student there from 1925 to 1929. Locke was the only member of her family to complete high school, and the only student in her class for her final two years of schooling. Locke wanted to be a writer, rather than a teacher or nurse, the conventional careers for literate women of her generation. She won a scholarship to study at the University of Auckland, where she became known as "Little Farrelly". She started in 1930, at the beginning of the Depression, and Locke struggled for income – she lived off a mixture of scholarships and part-time jobs, such as working at the Parnell Public Library. She became involved in printing the early literary magazine, Phoenix, and though she did not write for the magazine, her flat was a central base for all those involved. In 1932 during her time at the university, Locke had an experience that would become a major influence on her future political ideology and activism, according to her daughter, Maire Leadbeater. This "watershed experience" was the sight of 10,000 unemployed men marching down Queen Street, which according to Leadbeater instilled in Locke an ambition "to be one with all who struggled and all who were oppressed".

When the last of the ten thousand had passed me, I was left on the pavement to answer the question these men had silently flung at me: whose side are you on? Whoever you are, and wherever you are going, I am going too, I had answered.

— Elsie Locke, Student at the Gates (1981), p. 98

Locke gained an increasing interest in socialism during her studies, and attended meetings of Friends of the Soviet Union, and the Fabian Society. In 1932 she organised a Working Women's Convention, and the following year she graduated university with a BA, and joined the Communist Party.

Locke wrote of her early life and education in her 1981 autobiography, Student at the Gates, which discusses the influences which shaped her socialist philosophies, and some of New Zealand's dominant political and literary personalities of the 1920s and 1930s.