Justice Felix Reginald Dias Bandaranaike I (Sinhala: ෆෙලික්ස් රෙජිනල්ඩ් ඩයස් බණඩාරනායක; 26 July 1861 – 30 January 1947) was a Ceylonese (Sri Lankan) judge and lawyer. He was a Judge of the Supreme Court of Ceylon. Born to Rev. Canon Samuel William Dias Bandaranaike, he was educated at S. Thomas' College and the Colombo Academy. He went on to Trinity Hall, Cambridge gaining a MA and LLM from the University of Cambridge. He apprenticed to Henry Fielding Dickens, KC and was admitted to the Inner Temple in 1887 and took oaths as an Advocate in Ceylon in 1888.