Kelleher was born on 11 June 1875 at 25 King Street, in
Cork City, to William Kelleher (an accountant) and Helena Walsh. 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 (and MA 1905). In 1910 he was appointed assistant to the Professor of Natural Philosophy there, and in 1914, he was appointed Erasmus Smith's Professor of Mathematics. He died on 18 August 1917, due to
sarcomatosis asthenia. ==Family==