HMCS Lady Evelyn was a commissioned patrol boat of the Royal Canadian Navy during the First World War.

Originally built as a passenger liner, Deerhound, she was acquired in 1907 by the Canadian government and renamed Lady Evelyn for use by the post office.

[4] Canada's Postmaster General purchased Deerhound in 1907 at a cost of some $65,000 to act as a mail tender for transatlantic steamers.

Renamed Lady Evelyn, she met ocean liners in the Gulf of St. Lawrence to transfer mail to and from trains at Rimouski, Quebec in order to speed its delivery.

[5] In 1914 Lady Evelyn was involved in the rescue of survivors from RMS Empress of Ireland when that ship sank following a collision off Rimouski.