Henry Joseph Macaulay Barnett CC (10 February 1922 – 20 October 2016), known by his colleagues and friends as "Barney", was a Canadian physician and neurologist.

After medical school, he did postgraduate training in Neurology in Toronto, London and Oxford, working under Charles Symonds, Hugh Cairns and Richard Doll.

His neurology service at Sunnybrook Hospital occupied 70 beds and he first recognized violent effort neuropathy, onion-picker's neuropathy, carotid stump syndrome, stroke from mitral prolapse, external carotid artery steal, post-traumatic syringomyelia, tumor-related syringomyelia, and published on these clinical syndromes.

He served as its chief editor from 1982 to 1987 and ultimately, his own biography appeared in that journal, written by his disciple-neurologists J David Spence and Vladimir Hachinski.

Results were presented in weekly clinico-pathologic conferences[4] that everyone in the Department of Clinical Neurological Sciences, both faculty and residents in training, would compulsorily attend.

By inhibiting the enzyme cyclooxygenase, aspirin blocks the production of thromboxane in platelets, potentially reducing clot formation and preventing ischemic stroke.

After obtaining funding from the Medical Research Council of Canada, in 1978, Barnett published the results from 585 patients in his randomized clinical trial demonstrating the effectiveness of aspirin in preventing stroke.

[5] Barnett applied to the NIH for a grant to study the effectiveness of then commonly performed cerebral bypass surgery, which re-routed blood flow from the extracranial to the intracranial circulation.

[6] Many patients with focal ischemic stroke arising from the carotid artery or the heart were saved from needless surgery as a result, but the surgical procedure may still find usefulness in diseases that are related to more global, slow reduction of cerebral blood flow over longer time periods, such as Moyamoya disease,[9] giant aneurysms[10] or skull base surgery requiring sacrifice of major vessels for tumor removal.

[7] European centres were finding similar results,[13] and thus Dr. Barnett spearheaded the establishment of carotid artery surgery for preventing stroke.

The Heart and Stroke Foundation of Canada's Henry JM Barnett Research Scholarship Award is named in his honor.

The small, brown-streaked finch with a yellow bill had successfully impaled a mouse on a hawthorn tree and the young lad was hooked on ornithology for life.