Cardinal Bishops, or Cardinals of the Episcopal Order, are among the most important persons in the Roman Catholic Church.

Originally this term referred specifically and exclusively to the men named to head the six suburbicarian dioceses, who include the Dean of the College of Cardinals. In 1965 Pope Paul VI decreed in his motu proprio Ad purpuratorum patrum that Eastern Rite patriarchs who were named Cardinals would also be part of the episcopal order, ranked after the six Cardinal Bishops of the suburbicarian sees (who had been rendered strictly titular bishops of those sees by Pope John XXIII three years earlier). The Dean continues to always be one of the six suburbicarian bishops, though now elected by the six from their number rather than necessarily the longest-serving. The Latin Rite Patriarchs of Lisbon and Venice, while always made Cardinals at the consistory after they take possession of their sees, are made Cardinal Priests, not Cardinal Bishops.

The Cardinal Bishops are the only order of Cardinals who have always been required to be bishops, and in former times when a Cardinal of one of the lower orders became a Cardinal Bishop he was consecrated a bishop on that occasion. Since 1962 all Cardinals have been bishops with rare exceptions, but those excepted cardinals allowed to decline episcopal consecration remain therefore ineligible to be Cardinal Bishops.

For a period ending in the mid 20th century, long-serving Cardinal Priests were entitled to fill vacancies that arose among the Cardinal Bishops, just as Cardinal Deacons of ten years' standing are still entitled to become Cardinal Priests. Since then Cardinals have been advanced to Cardinal Bishop (except for the Eastern Rite Patriarchs, no one ever joins the College of Cardinals as a Cardinal Bishop) exclusively by Papal appointment. Only leading figures close to the Pope can expect to be appointed. Prior to his April 19, 2005, election as pope, the Dean was the long-serving head of the Congregation for the Doctrine of the Faith, Joseph Cardinal Ratzinger (now Pope Benedict XVI); the Vice-Dean is the long-serving Cardinal Secretary of State, Angelo Cardinal Sodano; the retired Dean, Bernardin Cardinal Gantin, is the senior prelate from Africa and long headed the Congregation for Bishops, which selects candidates for bishops throughout the world; Roger Cardinal Etchegaray, who succeeded Cardinal Gantin as President of the Pontifical Council for Justice and Peace when Cardinal Gantin moved to head the Congregation for Bishops, is one of Pope John Paul II's longest-standing Vatican aides; and the two younger suburbicarian bishops, Alfonso Cardinal Lopez Trujillo, head of the Pontifical Council for the Family and a leading figure in the Latin American church, and Giovanni Battista Cardinal Re, who now heads the Congregation for Bishops, are likewise seen as very important figures.

The three current Eastern Rite patriarchs are the head of the Vatican's Congregation for the Oriental Churches and former Patriarch of Antioch for the Syrians Ignace Cardinal Daoud, the Coptic Catholic Patriarch of Alexandria Stéphanos II Cardinal Ghattas , and the Patriarch of Antioch for the Maronites Nasrallah Cardinal Sfeir.