Nirmala Rajasingam is a Sri Lankan Tamil author and activist who lives in London. She is a member of the steering committee of the Sri Lanka Democracy Forum (SLDF), an international network of progressive diaspora voices. She was the first woman to be detained under the Prevention of Terrorism Act in the early 1980s, survived the government-engineered Welikade prison massacre, and was subsequently freed from prison by LTTE guerrillas. She left the LTTE as a result of the lack of internal democracy within the movement and its serious human-rights abuses.

Nirmala Rajasingam is the sister of Rajani Thiranagama, founder-member of the University Teachers for Human Rights (Jaffna), who was assassinated for her outspoken views. They are the subjects of the documentary film No More Tears Sister (National Film Board of Canada).