A missionary is a member of a religious group sent into an area to do evangelism or ministries of service, such as education, literacy, social justice, health care and economic development. The word "mission" originates from 1598 when the Jesuits sent members abroad, derived from the Latin missionem (nom. missio), meaning "act of sending" or mittere, meaning "to send". The word was used in light of its biblical usage; in the Latin translation of the Bible, Christ uses the word when sending the disciples to preach in his name.

The term is most commonly used for Christian missions, but can be used for any creed or ideology.

A Christian missionary can be defined as "one who is to witness across cultures." The Lausanne Congress of 1974, defined the term, related to Christian mission as, "to form a viable indigenous church-planting movement." Recognizing justice as being at the heart of the Gospels, some modern missionaries now promote the development of western government^{[citation needed]}, education and economic structure^{[citation needed]} in the place of pre-existing local systems and tradition. Missionaries can be found in many countries around the world.

Philip James Elliot (October 8, 1927 – January 8, 1956) was an evangelical Christian who was one of five missionaries killed while participating in Operation Auca, an attempt to evangelize the Waodani people of Ecuador.

Elliot was born in Portland, Oregon, to Fred and Clara Elliot. Fred was of Scottish heritage; his grandparents were the first of his family to settle in North America. Clara's parents moved near the turn of the 20th century from Switzerland to eastern Washington, where they operated a large ranch. They met in Portland, where Clara was studying to be a chiropractor and Fred, having devoted himself to Christian ministry, was working as a traveling preacher in a small Baptist church. After two years of correspondence, they were married in 1918. Robert, their first child, was born in 1921 while they were living in Seattle, and he was followed by Herbert, Jim, and Jane, all three of whom were born after the family moved to Portland. Elliot's parents had firm Christian beliefs, and they raised their children accordingly, taking them to church and reading the Bible regularly. Elliot professed faith in Jesus at the age of six and grew up in a home where obedience and honesty were enforced. The Elliot parents encouraged their children to be adventurous, and encouraged them to "live for Christ".