Sir Thomas Barlow, 1st Baronet, was born on September 4, 1845, in Edgeworth, Lancashire, England.

He was a British royal physician known for his research on infantile scurvy. He graduated from University College London with a B.M. in 1873 and an M.D. in 1874. He first worked as a registrar at Great Ormond Street Hospital and later became a physician and consultant in 1899. From 1895 to 1907, he served as a Professor of Pediatrics and Clinical Medicine at University College London. In 1883, his research proved that infantile scurvy was identical to adult scurvy. Barlow's disease, also known as infantile scurvy, is named after him.

Sir Barlow served as a Royal Physician to Queen Victoria, King Edward VII, and King George V. He was knighted as a Knight Commander of the Royal Victorian Order in 1901 and created a Baronet of Wimpole Street in St. Marylebone, London in 1902. He also served as President of the Royal College of Physicians from 1910 to 1914 and delivered their Harveian Oration in 1916 on the subject of Harvey, The Man and the Physician. In 1918, he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences. Sir Barlow received the honorary degree of Doctor of Science (D.Sc.) from the Victoria University of Manchester in 1902. He was also listed as honorary medical staff at King Edward VII's Hospital for Officers in 1904.

In 1880, he married Ada Helen Dalmahoy (1843–1928). He died on January 15, 1945, in London, England.