Leo Patrick Joseph O'Brien (2 July 1907 – 13 March 1997) was an Australian cricketer and sportsman who played in five Test matches between 1932 and 1936.

James immigrated, with his two brothers, from Kells, Ireland during the 1850s Victorian Gold Rush period.

O'Brien was a very determined left-handed batsman who played for the Richmond Cricket Club, now known as the Monash Tigers before making his debut for Victoria in the 1929–30 season.

[3] As an all round sportsman, and in a rare coincidence, Mentone's only senior football premiership teams of 1928 and 1956, included Mentone Cricket Club's only two Test cricket players, Leo O’Brien and Ian Meckiff.

[4] A large part of his working life was spent as a public servant with the Australian Taxation Office.