"Svefn-g-englar" is a song by the Icelandic post-rock band Sigur Rós, from their second album, Ágætis byrjun.

"Svefn-g-englar" was released as a single in 1999, with two studio recordings — "Svefn-g-englar" (an Icelandic pun mixing "sleepwalkers" and "sleep angels") and "Viðrar vel til loftárása" ("good weather for airstrikes"), both from Ágætis byrjun — and two songs recorded live at the Icelandic Opera House located in Reykjavík — "Nýja lagið" ("new song"), which was never recorded in studio, and "Syndir Guðs" ("God's sins"), from the group's first LP, Von.

The single was the first UK release for the band, issued on Fat Cat Records in 1999.

[4] The single is available both on compact disc and 12 inch vinyl, with somewhat different selections of tracks, including "Veröld ný og óð" ("new and old world").

[5] The video features the Perlan special-needs theatre group, an Icelandic acting troupe of men and women with Down syndrome.