Thomas Addis Jr. (27 July 1881 – 4 June 1949) was a Scottish physician-scientist from Edinburgh who made important contributions to the understanding of how blood clots work.
Towards the end of his life Addis began to study laboratory rats as a model of proteinuria, and was among the first people to note the presence of rodent major urinary proteins.
Shortly before his death, he was expelled from the American Medical Association for refusing to pay his annual membership fee, which he did to protest the AMA's lack of support for President Truman's national health insurance plan.
His Stanford colleague Frank W. Weymouth wrote about him: Injustice or oppression in the next street ... or any spot inhabited by men was a personal affront to Thomas Addis and his name, from its early alphabetical place, was conspicuous on lists of sponsors of scores of organizations fighting for democracy and against fascism.
Tom Addis was happy to have a hand in bringing to the organization of society some of the logic of science and to further that understanding and to promote that democracy which are the only enduring foundations of human dignity.