| Honorific-Prefix: | The Honourable |
| Sir William Hall-Jones | |
| Honorific-Suffix: | KCMG |
| Order: | 16th Prime Minister of New Zealand |
| Term Start: | 10 June 1906 |
| Term End: | 6 August 1906 |
| Predecessor: | Richard Seddon |
| Successor: | Joseph Ward |
| Birth Date: | 1851 |
| Birth Place: | Folkestone, Kent, England |
| Death Date: | 1936 |
| Party: | Liberal |
| Constituency: | Timaru |
Sir William Hall-Jones, KCMG (16 January 1851 - 19 June 1936) was Prime Minister of New Zealand from June 1906 until August 1906. He was the interim Prime Minister after the death of Richard Seddon and the return from overseas of Sir Joseph Ward.
Hall-Jones was born in Folkestone, Kent, England, landed at Dunedin in 1873 and became a carpenter and later a builder in Timaru. In August 1890 he was elected to represent Timaru in the House of Representatives, a seat he held until his resignation in October 1908. He was an Independent but had moderate, progressive views that tended to align him with John Ballance, Sir George Grey and John McKenzie.
Hall-Jones became a cabinet minister in 1896, was acting Prime Minister during the absence from the country of Richard Seddon in 1906 and formed an administration immediately after Seddon's funeral.
However he announced that he would only hold power until Sir Joseph Ward's return from abroad. He accepted the Railways and Public Works portfolios in the subsequent Ward administration. He succeeded William Pember Reeves as High Commissioner for New Zealand in London in December 1908, returned to New Zealand at the end of his term in 1912, and was appointed to the Legislative Council by Massey.
Hall-Jones was a mild mannered man with a fully earned reputation as an outstanding administrator.
The Bateman New Zealand Encyclopedia, 1988