| Honorific-Prefix: | The Honourable Sir |
| Mellis Napier | |
| Office: | Chief Justice of South Australia |
| Term Start: | 25 February 1942 |
| Term End: | 28 February 1967 |
| Predecessor: | Sir George Murray |
| Successor: | John Bray |
| Term Start2: | 30 April 1942 |
| Term End2: | 3 September 1973 |
| Predecessor2: | Sir George Murray |
| Successor2: | Sir Walter Crocker |
| Office3: | Judge of the Supreme Court of South Australia |
| Term Start3: | 28 February 1924 |
| Term End3: | 28 February 1967 |
| Predecessor3: | John Gordon |
| Successor3: | John Bray |
| Office4: | Chancellor of the University of Adelaide |
| Term Start4: | 21 October 1947 |
| Term End4: | 29 September 1961 |
| Predecessor4: | William Mitchell |
| Successor4: | George Ligertwood |
| Birth Date: | 1882 10, df=yes |
| Birth Place: | Dunbar, East Lothian, Scotland |
| Death Place: | Kingswood, South Australia |
Sir Thomas John Mellis Napier (24 October 1882 – 22 March 1976) was an Australian judge and academic administrator. He was a judge of the Supreme Court of South Australia (1924–1967), Chief Justice of South Australia (1942–1967), and Chancellor of the University of Adelaide (1948–1961).
Thomas John Mellis Napier was born in Dunbar in East Lothian to Dr. Alexander Disney Leith Napier FRSE and his wife Jessie Mellis. The family moved to London in 1887, where he attended the City of London School, and emigrated to Australia in 1896, Alexander Napier having taken the post of senior resident physician at the Royal Adelaide Hospital.[1]
Thomas Napier studied law at the University of Adelaide, graduating LLB in 1902.[1]
In 1903 Napier became managing clerk for Kingston & McLachlan, and became a partner with McLachlan in 1906.[1]
He was appointed judge of the Supreme Court of South Australia in 28 February 1924, serving until 28 February 1967, and served as Chief Justice of South Australia from 25 February 1942 until 28 February 1967.
In 1964, Napier presided over the trial of Glen Sabre Valance, the last man hanged in South Australia. Valance was also the second-to-last man to be executed in Australia overall.
In 1912, together with Thomas Poole, Napier resuscitated the Law Society of South Australia, and served as its vice president in 1923.[2]
Napier was Chancellor of the University of Adelaide from 1948 to 1961.[3]
On 24 October 1908 Napier married Dorothy Bell Kay (died 1959) at Walkerville. They had three sons, one of whom was killed whilst serving with the Royal Australian Air Force in 1944.[1]
He died on 22 March 1976 at Kingswood, South Australia and, following a state funeral, was cremated.[7]