Calamur Viravalli Sundara Sastri (also spelt Sundram or Sundaram, and Sastry, Sastriar, Sastriyar, or Sastrigal) was a leading Vakil of the High Court of Madras, second in the Calamur line to bear the style Viravalli, and of a family line occupying a prominent position within the Madras Presidency; a "giant" of Madras jurisprudence, with a "very large" practice on the Original Side, which he shared with his partner and adoptive brother, Sir P. Ananda Charlu. Sundara Sastri published a Revised Set of the Rules of Practice for Original side litigation, which became de rigueur, and was noted as an orator with 'perfect' diction. He authored the SundararÃÂmÃÂyaá¹Âa.
Alongside K. P. Viswanatha Iyer, Sir C. Sankaran Nair, P.V. Krishnaswami Chetty, Sir V. Bhashyam Iyengar, and Sir P Ananda Charlu, he was one of only six Vakils to occupy two sets of chambers simultaneously.