Francinete de Lima Oliveira was a nurse and teacher from Brazil.
Geraldo Gomes de Oliveira was a canvasser, evangelist, pastor, and teacher in South America.
Gideon de Oliveira was a physician, theologian, teacher and lecturer in Brazil.
Manoel Rosa de Oliveira was a pastor, evangelist, canvasser, and teacher from Brazil.
Modesto Marques de Oliveira was a teacher, pastor, and administrator in Brazil. Modesto was raised in an Adventist home.
Saturnino Mendes de Oliveira was a canvasser, and Bible instructor from Brazil.
Charles Gilbert and Verneita Oliver served as missionaries in Japan, Guam, and Indonesia, he as a church administrator, and she as a nurse.
Erich Willy Olm was an administrator and lawyer from Brazil.
Ricardo Olmserved as a Bible instructor, teacher, and missionary in South America.
Olmeca Conference was organized in 2001, when Tabasco Conference was divided into the Tabasco Conference and the Olmeca Conference.
Mahlon Ellsworth Olsen was an eminent Adventist health advocate, denominational historian, and educator who pioneered distance education. He was the second son of Ole Andres Olsen (July 28, 1845-January 29, 1915), president of the General Conference from 1888 to 1897.
The Norwegian Olaf Johan Olsen, also known as Iceland-Olsen and the Apostle to Iceland, had a remarkable mission career in the Seventh-day Adventist Church as a missionary pastor, leader, and administrator. In Iceland, over a period of 33 years, he raised up the local church from almost nothing to eight congregations, second only to the Lutheran State Church.
A Norwegian-born American, Ole Andres Olsen served the Seventh-day Adventist Church as a minister and senior administrator for forty-four years, becoming one of the most experienced international leaders of the movement’s second generation. He was elected as president of the General Conference at the age of forty-three and served four terms (1888–1897), providing diplomatic, spiritually sensitive, forward-thinking leadership through a difficult period of doctrinal conflict, deep financial depression, and rapid expansion that exposed the inadequacies of the denomination’s organizational structure.
The Omaura School of Ministry is located in the Eastern Highlands of Papua New Guinea (PNG), at an altitude of 4,650 feet (1,417 meters). It was originally established as the Omaura Training School, “for the purpose of training workers to carry the message to the multiplied thousands of the great inland who have not yet been reached by any mission influence.”
Daniel Kayode Omoleye was a pastor, church planter, evangelist, and church administrator from Nigeria.
Abel Nyakundi Onchoke was a pastor, educator and administrator from Kenya.
Ondo Mission, formerly South West Nigeria Conference, was organized in 1998, and reorganized and renamed in 2013. Ondo Mission covers the present Ondo state of the Federal Republic of Nigeria.
Joseph Shem Onyango was a church pioneer, pastor, preacher, evangelist, and marriage counselor from Tanzania.
Open Heart International (OHI) is a medical outreach program originally started by Sydney Adventist Hospital in 1986. It has conducted more than 188 surgical projects in 16 countries. OHI’s volunteer teams provide cardiac, plastic, reconstructive, orthopedic, women’s health, and eye surgery.
Ole Oppegard, a pioneer from Norway, served in Argentina as a literature evangelist and as the first Adventist missionary in South America dedicated to medical missionary efforts.