Sir Gerald Gray Fitzmaurice GCMG QC (24 October 1901 – 7 September 1982)  was a British barrister and judge. He was a member of the Permanent Court of Arbitration between 1964 and 1973 and a Senior Judge of the International Court of Justice between 1967 and 1973, before becoming a Judge of the European Court of Human Rights at Strasbourg in 1974.
He was born on 24 October 1901, the younger son of Vice-Admiral Sir Maurice Swynfen Fitzmaurice and Mabel Gertrude Gray. He studied at Malvern College and at Gonville and Caius College, Cambridge, where he gained a Bachelor of Laws in 1922. He became a Barrister-at-Law at Gray's Inn in 1925 and worked for the Foreign Service from 1929. He spent time as the Second Legal Advisor from 1945 until 1953, having been invested as a Companion of the Order of St Michael and St George in 1946. Also that year he was part of the United Kingdom's delegation to the UN Assembly.
Fitzmaurice was the UK Counsel to the International Court of Justice at The Hague between 1948 and 1954 and served as the Senior Legal Advisor between 1953 and 1960. In 1954 he was advanced to a Knight Commander of the Order of St Michael and St George. In 1956, he was appointed Vice-President of the Grotius Society. Fitzmaurice was a member of the International Law Commission of the UN between 1955 and 1960, and was made a Queen's Counsel in 1957. In 1960, he was appointed a judge at the International Court of Justice, the main judicial organ of the United Nations, and he held that position until 1973. He was made a Knight Grand Cross of Order of St Michael and St George in 1960, and the following year became a Bencher of Gray's Inn.
Fitzmaurice was a member of the Permanent Court of Arbitration between 1964 and 1973 and a Senior Judge of the International Court of Justice between 1967 and 1973. He became a Judge of the European Court of Human Rights at Strasbourg in 1974. During his long career in the law he received honorary degrees of Doctor of Law from the University of Edinburgh in 1970 and the University of Cambridge in 1972.
He married Alice Evelina Alexandra Sandberg on 15 September 1933 and the couple had two sons, James Alexander Swynfen Fitzmaurice (born 6 July 1936) and Maurice Evelyn Forbes Fitzmaurice (born 26 February 1939).
- Judge Sir Gerald Fitzmaurice and the Discipline of International Law: Opinions on the International Court of Justice, 1961-1973, J. G. Merrills, ed. (Martinus Nijhoff, 1998) p99
- Montgomery-Massingberd. Burke's Irish Family Records. p. 435.
- Montgomery-Massingberd, Hugh (1976). Burke's Irish Family Records. London: Burkes Peerage Ltd.
- Sir Gerald Gray Fitzmaurice. thepeerage.com