This is the case in which Supreme Court held that Right to Privacy is a fundamental right as a part of Article 21.
Justice K.S.Puttaswamy(Retd) & Anr Vs Union Of India & Ors on 11 August, 2015Justice K.S.Puttaswamy(Retd) & Anr Vs Union Of India And Ors. on 24 August, 2017
Justice K.S.Puttaswamy(Retd) & Anr Vs Union Of India And Ors. on 26 September, 2018
List of other case laws around Article 21 are here.