Alexander Nicolson was a Scottish lawyer and Gaelic scholar. He was sheriff-substitute of Kirkcudbright and Greenock, and pioneer of mountain climbing in Scotland.

Giving up theology while at the Free Church College, Nicholson for some time worked as one of the sub-editors of the eighth edition of the Encyclopædia Britannica. He moved on, to the staff of the Edinburgh Guardian, a short-lived literary paper of high literary quality. For a year he edited an advanced Liberal paper, the Daily Express, which later was merged into the Caledonian Mercury.

Nicolson was called in 1860 to the Scottish bar. For ten years he reported law cases for the Scottish Jurist, of which he became editor. He acted as examiner in philosophy in the university, and examiner of births, etc., in Edinburgh and the neighbouring counties.

In 1883 Nicolson was appointed to the Napier Commission on the condition of the crofters because of his expertise on Gaelic culture. He was reponsible for the Commission's recommendation that Gaelic should be made a "specific subject" in schools and eligible for grants.