Brigadier Brian Thomas McMahon CBE KStJ (born 1929) is a retired New Zealand Defence Force officer.

[3] McMahon began a career in the New Zealand Defence Force in 1966 as resident medical officer at the Waiouru Military Camp.

[2] He left Vietnam in 1970,[5] and later served in the United Kingdom, Singapore and Malaysia, the latter occasion as medical officer to the 1st Battalion, Royal New Zealand Infantry Regiment.

[6] In 1998, McMahon returned to Vietnam to reopen a hospital at Bong Son that had been destroyed during the war.

During the trip he visited the site where a friend and sergeant had been killed by a land mine in front of McMahon.

[2][7] He was also appointed the first patron of the University of Otago Medical School Brain Health Research Centre.

[2] In 2019, a scholarship was established in McMahon's name for second-year Bachelor of Health Science students at Auckland University of Technology.