Events that occurred on 27 March.
 On Earth
- 1928 - Tolkien works on the latter part of Canto IV of Lay of Leithian.
- 1939 - J.R.R. Tolkien does the first of his three days' training with the top-secret Government Code and Cypher School (GCCS) at their London headquarters.
- 1972 – Rayner Unwin organizes a party in celebration of J.R.R. Tolkien's CBE the following day.