Father James Cullen, S. J. (April 19, 1867 – December 7, 1933) was born at Drogheda, Co Meath, Ireland. He studied mathematics at the Trinity College, Dublin for a while, but eventually turned into theology and was ordained on July 1, 1901. In 1905, he taught mathematics at Mount St. Mary's College in Derbyshire and published his finding of what is now known as Cullen numbers in number theory.
Keller, Wilfrid (1995). New Cullen primes. Math. Comp. 64, 1733–1741.