Thomas Addison (1793 - June 29, 1860) was a physician at Guy's Hospital who worked in the team of doctors led by Sir Astley Paston Cooper. Brilliant lecturer and clinical teacher, he is known for describing a wide range of diseases not only as was practiced at that time in terms of symptoms but primarily in terms of organs. He made one of the first adequate accounts of appendicitis and wrote a valuable study of the actions of poisons.

His name was recorded in the annals of medicine chiefly because of his descriptions of pernicious anemia (or Addisonian anemia) and Addison's disease (the adrenal glands insufficiency). In 1855 he published an important work: The Constitutional and Local Effects of Diseases of the Suprarenal Capsules.