J. Douglas MacMillan (30 September 1933 – 3 August 1991) was a British Christian minister in the Free Church of Scotland.

MacMillan was born the youngest of six children, on the Ardnamurchan peninsula in Argyll.

He was converted at the age of 21, and studied at the University of Aberdeen and at the Free Church College.

Since 1994, the biennial MacMillan Lecture in Evangelism has been held at that institution in his honour.

[1] According to Hywel Jones, MacMillan's preaching was marked by "powerful originality and strong orthodoxy".