The Solemnity of Our Lord Jesus Christ, King of the Universe, commonly referred to as the Feast of Christ the King, Christ the King Sunday or Reign of Christ Sunday, is a feast in the liturgical year which emphasises the true kingship of Christ. The feast is a relatively recent addition to the liturgical calendar, instituted in 1925 by Pope Pius XI for the Roman Rite of the Catholic Church.

In 1970 its Roman Rite observance was moved from October to the last Sunday of Ordinary Time and thus to the end of the liturgical year. The earliest date on which the Feast of Christ the King can occur is 20 November and the latest is 26 November.

The Lutheran, Anglican, Moravian, Methodist, Nazarene, Reformed and United Protestant churches also celebrate the Feast of Christ the King, which is contained in the Revised Common Lectionary; the Methodist, Anglican and Presbyterian Churches often observe this as part of the liturgical season of Kingdomtide, which runs between the Fourth Sunday before Advent and the Feast of Christ the King. It is also observed on the same computed date as the final Sunday of the ecclesiastical year, the Sunday before the First Sunday of Advent, by Western Rite parishes of the Russian Orthodox Church Outside Russia. Roman Catholics adhering to the Extraordinary Form of the Roman Rite use the General Roman Calendar of 1960 and continue to observe the Solemnity on the date established in 1925, the final Sunday of October.

Final Sunday of the Liturgical Calendar (being the Sunday before the First Sunday of Advent); 
from 20–26 November, inclusive (in Ordinary Form), or final Sunday of October (in Extraordinary Form)