John Thomas Fitzsimons (3 March 1915 – 3 September 1995) was a Scottish footballer who played as an outside left, and a medical doctor who acted as Celtic F.C.'s club physician for 34 years, also working for the Scotland national football team in the role.^[1]

He began his senior football career at Celtic in 1934, also training for his medical qualifications at the Anderson College of Medicine^[2] (then associated with the University of Glasgow but today an integral part of the University of Strathclyde). Due in part to his educational commitments he was only a fringe player at the Hoops (five Scottish Division One appearances in four seasons),^[3] and transferred to lower division Alloa Athletic in 1938.^[4] During World War II when the usual competitions were suspended for seven years, he switched to Clyde then Falkirk,^[5] where he made over 150 appearances in total, played on the losing side in the 1943 Southern League Cup final^[6][7][8] and was still with the Bairns when official competitions resumed in 1946,^[9] though by the end of that year he had signed for Hamilton Academical,^[10] soon making a return to Clyde before retiring from playing in 1948.^[11]

In his medical career, Fitzsimons worked at Belvidere Hospital (Parkhead) then as a GP in his native Glasgow.^[12] In 1953 he was appointed as Celtic's club doctor, a position he held until 1987 spanning the highly successful period under manager Jock Stein. He had a similar occasional role with the Scottish international squad from 1970 to 1982, accompanying them to three FIFA World Cup finals tournaments.^[1] He was made a Knight of the Order of St. Sylvester by Pope Paul VI in 1976 for his commitment to the local Lourdes Hospitalité pilgrimage foundation.^[13][14]