Adon Olam (Hebrew: אֲדוֹן עוֹלָם‎‎; "Eternal Lord" or "Lord of the Universe") is a strictly metrical hymn in the Jewish liturgy written in Iambic tetrameter. It has been a regular part of the daily and Sabbath liturgy since the 15th century.

According to the custom of the Sephardim and in British synagogues generally, it is congregationally sung at the close of the Sabbath and festival morning services, and among the Ashkenazi Jews also it often takes the place of the hymn Yigdal at the close of the evening service on these occasions, while both hymns are almost universally chanted on the Eve of Atonement (Kol Nidre). Because of this solemn association, and on account of its opening and closing sentiments, the hymn has also been selected for (tuneless) reading in the chamber of the dying, and in some congregations it is recited (subdued and tuneless) in the synagogue as a means of reporting a death in the community. It is likewise recited or chanted at the commencement of the daily early morning prayer, that its utterance may help to attune the mind of the worshiper to reverential awe. When it is sung at the end of the service, the congregation sits while singing it, as a demonstration that they are not eager to leave the house of prayer but were willing to stay and continue praying (by starting again at the beginning of the day's prayers).