Michael William O'Callaghan (born 27 April 1946) is a former New Zealand rugby union player.
A wing three-quarter, O'Callaghan represented Manawatu and Waikato at a provincial level, and was a member of the New Zealand national side, the All Blacks, in 1968.
He played three Test matches for the All Blacks against the touring French team that year.
[1] He then undertook doctoral studies at the University of Cambridge; the title of his thesis, completed in 1978, was Assessment of sino-atrial and atrio-ventricular nodal function in the conscious horse by intra-atrial electrostimulation.
[3] O'Callaghan married New Zealand scholar of French culture, Raylene Ramsay, in Poitiers in 1971.