Stephen Barnabus Kelleher (1875–1917) was an Irish mathematician who served as Erasmus Smith's Professor of Mathematics at Trinity College Dublin (TCD) from 1914 to 1917.
He attended Christian Brothers schools in the city and then studied mathematics at Queen's College Cork (BA 1895, MA 1896).
Moving to Dublin, he took another mathematics degree at TCD (BA 1902, large gold medal), where he became a Scholar in 1900 and became a Fellow in 1904[2] (and MA 1905).
Kelleher was on the Royal Commission to draw up a plan for the establishment of a university in Ireland that would be satisfactory to Catholics.
As a TCD man, be believed that it would be "a grave danger to the interests of Irish lay Catholics and a menace to the future peace of the country".