Angel

Angels, known in the mythology of many species, were spiritual beings that served gods and other higher powers as their messengers.

Appearance
Popular Earth depictions of angels often presented them as beautiful humans with halos and/or wings, not unlike Solonians in their "evolved form", (TV: The Mutants) Light (TV: Ghost Light) and the Weeping Angels. (TV: Blink) Members of the Heavenly Host, robots designed by Max Capricorn, resembled angels by deliberate design. (TV: Voyage of the Damned) James Court, who worked in Earth theatre in the late 20th century, had often observed a special effect wherein a "hastily-assembled combination of feathers, muslin and stage lighting" created the appearance of an angel from the audience's point of view. (PROSE: Vampire Science)

Life's angels indeed had "silvered wings". Made out of living crystalline substances, they had a number of blinking eyes each. Their singing was "sweet and honeyed". (PROSE: Hark! The Herald Angels Sing)

History
Angels were among the agents of the eternal being known as Life. Living beings carved out of crystals, they beat their silvered wings and blinked their many eyes, and were tasked with carrying news of cosmic importance throughout Creation to mortals and immortals alike. (PROSE: Hark! The Herald Angels Sing) Light, an Eternal himself, (PROSE: Divided Loyalties) who travelled the universe compiling the Catalogue of Life, took on the form of an angel when awakened on Earth in the 19th century. (TV: Ghost Light)

According to a popular narrative known to the Sixth Doctor, and William Shakespeare, there was once a War in Heaven fought amongst the angels. It concluded with Lucifer being cast down from Heaven and into Hell, barred from returning to the Eternal City; he was followed down from Heaven by his nemesis Gabriel, who continued fighting him ever after. (PROSE: Master Faustus, Academic Notes) Matthew Stobbold once told the Eighth Doctor, however, that the Devil's traditional archenemy was instead another archangel, Michael. (PROSE: The Burning)

Peri Brown once met an angel named Yy, who was "more than just woman or man", androgynous and "unbearably beautiful". They had fallen from Heaven, and after selling their wings for a cheeseburger, Yy was imprisoned on Sheol. Peri convinced Yy to return, and helped them close the Gates of Heaven. (PROSE: The Ruins of Heaven)

Iris Wildthyme, for her part, was well-acquainted enough with an archangel called Gabriel to play gin rummy with him for the Ark of the Covenant; (PROSE: The Unhappy Medium) it is worth noting that in his eighth incarnation, Iris's friend the Doctor once claimed that he and "the archangel Gabriel" were one of the same. (PROSE: Vampire Science)

When another War in Heaven (that which was fought between the Great Houses and the Enemy) seemed to be drawing to a close, thousands of angels descended from the heavens above the Shadow Spire, one of Faction Paradox's last outposts. With their singing, they announced the end of the War and the coming of the Peace. (PROSE: Hark! The Herald Angels Sing) Three were captured by the Crime Lady Cortalian and sold into slavery at the First Auction in Heaven. They were bought by a corrupt, lecherous Bishop, who intended to show them off to "his Holiness" to finally show up "the f*cking Protestants". The Angels rolled their many eyes at these statements. (PROSE: Going Once, Going Twice)