Pope Paul VI
The Society of Jesus - also known as the Jesuits - is a religious order of men, within the Catholic Church. Founded in 1540 by Ignatius of Loyola and nine companions, the Society now numbers [about] twenty thousand men and is present in more than one hundred countries. Most Jesuits (about three quarters) are priests, but there are also two thousand Jesuit brothers, and almost four thousand 'scholastics' (men studying for the priesthood).
Jesuits take vows of poverty, chastity and obedience, and live together in community.
They are engaged in a wide variety of works: there are Jesuit parish priests, spiritual directors, writers and teachers, but also actors, lawyers, doctors, sculptors and astronomers. All of these ministries, however, are part of the same mission, described by [a] recent General Congregation of the Society in these terms: "...in accordance with our charism, our tradition and the approval and encouragement of popes through the years, the contemporary Jesuit mission is the service of faith and the promotion in society of 'that justice of the Gospel which is the embodiment of God's love and saving mercy'."
(Source: The Jesuits in Britain)
To find out more, or if you're interested in becoming a Jesuit, check out the Jesuit Vocations website (click here if you're in Ireland).