Deshamanya Herman Leonard de Silva, PC (28 January 1928 – 7 April 2009) was a Sri Lankan lawyer and diplomat.

He was a former President and honorary life member of the Bar Association of Sri Lanka.

He was described as ""a master of the law, an eloquent speaker with the gift of presenting a case attractively, a good debater with a razor sharp intellect"" by Lakshman Kadirgamar[2] and SL Gunasekera has classed him as one of the greats in Sri Lankan Law along with his close friend and contemporary in the Attorney General Department Elanga Wikramanayake.

De Silva was appointed a Senior Attorney (now referred to as Presidents Counsel after the 1978 Constitutional reform) by the President, admitted to the Roll of Honour of St. Peter’s College in 1984 and awarded the title ‘Vishva Prasadini (Nithiya)’ by the Government of Sri Lanka in 1997 in recognition of contributions to the advancement of the law and subsequently the title Deshamanya.

The 2009 Bar Association Law Journal was dedicated to HL De Silva and the Bar Association awarded the Deshamanya H. L. De Silva Memorial award to the winner of a legal essay competition open to junior lawyers.