Transcribed for Cello, "Ellens dritter Gesang" ("Ellens Gesang III", D. 839, Op. 52, No. 6, 1825), in English: "Ellen's Third Song", was composed by Franz Schubert in 1825 as part of his Op. 52, a setting of seven songs from Walter Scott's 1810 popular narrative poem The Lady of the Lake, loosely translated into German.

It is one of Schubert's most popular works. Beyond the song as originally composed by Schubert, it is often performed and recorded by many singers under the title "Ave Maria" (the Latin name of the prayer Hail Mary, and also the opening words and refrain of Ellen's song, a song which is itself a prayer to the Virgin Mary), in musically simplified arrangements and with various lyrics that commonly differ from the original context of the poem. It was arranged in three versions for piano by Franz Liszt.

The piece was composed as a setting of a song (verse XXIX from Canto Three) from Walter Scott's popular narrative poem The Lady of the Lake, in a German translation by Adam Storck [de] (1780–1822), and thus forms part of Schubert's Liederzyklus vom Fräulein vom See. In Scott's poem, the character Ellen Douglas, the Lady of the Lake (Loch Katrine in the Scottish Highlands), has gone with her exiled father to stay in the Goblin's cave as he has declined to join their previous host, Roderick Dhu, in rebellion against King James. Roderick Dhu, the chieftain of Clan Alpine, sets off up the mountain with his warriors, but lingers and hears the distant sound of the harpist Allan-bane, accompanying Ellen who sings a prayer addressed to the Virgin Mary, calling upon her for help. Roderick Dhu pauses, then goes on to battle.

Schubert's setting is said to have first been performed at the castle of Countess Sophie Weissenwolff in the little Austrian town of Steyregg and dedicated to her, which led to her becoming known as "the lady of the lake" herself.

The opening words and refrain of Ellen's song, namely "Ave Maria" (Latin for "Hail Mary"), may have led to the idea of adapting Schubert's melody as a setting for the full text of the traditional Roman Catholic prayer, "Ave Maria". The Latin version of the "Ave Maria" is now so frequently used with Schubert's melody that it has led to the misconception that he originally wrote the melody as a setting for the "Ave Maria" prayer.

In 1825, Schubert composed a selection of seven songs from Scott's The Lady of the Lake. They were published in 1826 as his Opus 52.

The songs are not intended for a single performer: the three songs of Ellen are for a woman's voice with piano accompaniment, while the songs for Norman and Malcolm Graeme were intended for the baritone Johann Michael Vogl. Of the remaining two songs, one was for a male ensemble and the other for a female ensemble.

"Ellens Gesang I", D. 837, Raste Krieger, Krieg ist aus / "Soldier rest! the warfare o'er" "Ellens Gesang II", D. 838, Jäger, ruhe von der Jagd / "Huntsman, rest! thy chase is done" "Bootgesang" (Hail to the Chief), D. 835, Triumph, er naht / "who in triumph approaches", for male voice quartet "Coronach" (Deathsong of the women and girls), D. 836, Er ist uns geschieden / "He is gone to the mountain", for female choir.

"Normans Gesang", D. 846, Die Nacht bricht bald herein ("Night will soon be falling") "Ellens Gesang III" (Hymne an die Jungfrau / Hymn to the Virgin), D. 839, Ave Maria! Jungfrau mild / "Ave Maria! maiden mild!" "Lied des gefangenen Jägers", D. 843, Mein Roß so müd / "My steed is tired" Schubert composed the songs to the German texts. However, with the exception of No. 5, the songs were clearly intended to be published with the original English texts as well. This meant finding correspondences to Storck's sometimes quite free translations, which entailed significant difficulties.