Lydia Mackenzie Falconer Miller or Harriet Myrtle (1812 – 11 March 1876) was a Scottish children's writer.

[1] She was schooled at Inverness Academy and later in Edinburgh, where she lodged with the musician George Thomson, a friend of the poet Robert Burns.

Her husband was appointed to manage the periodical The Witness in Edinburgh and Lydia assisted and wrote contributions for the publication.

[1] Under the pseudonym Mrs Harriet Myrtle, she wrote about 20 educational and moral stories for children which were often adventurous and light-hearted.

In 1847 she anonymously published her only adult novel, Passages in the Life of an English Heiress, or, Recollections of Disruption Times in Scotland, the background drawn from her own and her husband's upbringing and their discussions.