The Glory Be, perhaps derived from Christ's command to the apostles to baptize "in the name of the Father, and of the Son and of the Holy Spirit," has been prayed since the first centuries of Christianity.
This hymn of praise to the triune God joins us with the heavenly hosts in glorifying God. With the Glory Be we also profess, in a formula against the heresies of Arius (who denied the divinity of the Son) and Macedonius (who denied the divinity of the Holy Spirit), our faith in the most fundamental and basic mystery of revelation: the mystery of the Holy Trinity.
-The Handbook of Prayers
Glory be to the Father, and to the Son, and to the Holy Spirit.
As is was in the beginning, is now, and ever shall be, world without end. Amen.
Gloria Patri, et Filio, et Spiritui Sancto.
Sicut erat in principio et nunc et semper et in saecula saeculorum. Amen.