The Society of Jesus (Societas Iesu, S.J., SJ or SI) is a Christian male religious order of the Roman Catholic Church. The members are called Jesuits. They are sometimes referred to colloquially as "God's Soldiers" or "God's Marines", because of the military background of the founder Ignatius of Loyola and the members' willingness to accept orders anywhere in the world and to live in extreme conditions where required. The society is engaged in evangelization and apostolic ministry in 112 nations on six continents. Jesuits work in education (founding schools, colleges, universities and seminaries), intellectual research, and cultural pursuits. Jesuits also give retreats, minister in hospitals and parishes and promote social justice and ecumenical dialogue.

Ignatius founded the society after being wounded in battle and experiencing a religious conversion. He composed the Spiritual Exercises to help others follow the teachings of Jesus Christ. In 1534, Ignatius and six other young men, including St. Francis Xavier and Bl. Pierre Favre, gathered and professed vows of poverty, chastity, and later obedience, including a special vow of obedience to the Pope. Rule 13 of Ignatius' Rules for Thinking with the Church said: "That we may be altogether of the same mind and in conformity [...], if [the Church] shall have defined anything to be black which to our eyes appears to be white, we ought in like manner to pronounce it to be black. " Ignatius' plan of the order's organization was approved by Pope Paul III in 1540 by the bull containing the Formula of the Institute. The opening lines of this founding document would declare that the Society of Jesus was founded to "strive especially for the propagation and defense of the faith and progress of souls in Christian life and doctrine. " The Society participated in the Counter-Reformation and later in the implementation of the Second Vatican Council in the Catholic Church. The society's founding principles are contained in the document Formula of the Institute, written by Ignatius of Loyola.

The Society of Jesus is consecrated under the patronage of Madonna Della Strada, a title of the Blessed Virgin Mary, and it is led by a Superior General, currently Adolfo Nicolás.

The headquarters of the society, its General Curia, is in Rome. The historic curia of St Ignatius is now part of the Collegio del Gesù attached to the Church of the Gesù, the Jesuit Mother Church.