Nicholas Colohan (1806 – 11 February 1890) was an Irish doctor and professor of medicine at Queen's University, Galway from 1849 to 1879.
He graduated with a medical degree from the University of Edinburgh in 1828, though without a surgical qualification.
Colohan was one of six doctors associated with Galway's Fever Hospital.
He married Sara, daughter of Dr. Thomas Whistler of Oranmore.
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