Mervyn Fonseka, OBE, KC (1897–1946) was a Sri Lankan lawyer.
He taught briefly at Royal College before he joined the legal service as a Crown Counsel in 1928, later serving as an assistant to the Attorney General.
He was appointed Solicitor General in 1943, succeeding M. W. H. de Silva.
[2] Foneska took silks as a King's Counsel that year and held the office until 1945.
During his tenure, he served as the acting Attorney-General.