Brian John O'Brien AO FTSE (27 February 1934 – 7 August 2020) was an Australian physicist and space scientist.

[3] After studying physics at Sydney University, O'Brien worked as a physicist in Antarctica.

For his radiation experiment, he was awarded the NASA Medal for Exceptional Scientific Achievement.

[2] He later moved to Perth with his wife, Avril, and headed the Environmental Protection Authority of Western Australia.

[4] O'Brien was elected a Fellow of the Australian Academy of Technological Sciences and Engineering (FTSE)[2] in 1993.