Nigel Tranter (November 23, 1909 – January 9, 2000) was a Scottish historian and author.

Nigel Tranter was born in Glasgow and educated at George Heriot's School in Edinburgh. He trained as an accountant and worked in Scottish National Insurance Company, founded by his uncle. In 1933 he married May Jean Campbell Grieve and had two children, Frances May and Philip. He joined the Royal Artillery and served in East Anglia in the Second World War.

From his childhood onwards, he took a great interest in castles and their associated history. As a result, in 1935, at age 25, he published his first book, The Fortalices and Early Mansions of Southern Scotland. Prompted on by his wife, he wrote his first novel, In our Arms our Fortune, which was rejected by the publishers. For the first novel that was published, Trespass in 1937, he didn't receive any payment since the publishing company had gone bankrupt. Over the next few years, he wrote several books which were adventurous and romantic novels about imaginary characters set in various periods of Scottish history. He also wrote several westerns under the pseudonym Nye Tredgold to provide additional income for his family.

Between 1962 and 1971 he published the landmark series in five volumes, The Fortified House in Scotland. This covered the history and structure of every castle and similar structure in Scotland, 663 buildings in all and is still well worth reading for those who have an interest in this specialist area.

While researching the castles, Tranter realised that there were many characters and incidents in Scottish history which could be used as the basis for novels, which he tried to make as accurate as possible - while making no effort to hide his own strong Scottish identity. This was the direction which his writing then took, starting with the Master of Gray in 1961, telling the story of Patrick of Gray and his plotting to release Mary Queen of Scots. He continued in this vein until his death, producing carefully researched historical novels about real people and events. These novels have gained a wide readership while providing a basic grounding in Scottish history to their readers.