From the Hebrew name גַבְרִיאֵל (Gavri’el) which has been translated many different ways, but is generally agreed to mean “strong man of God” or “God is my strength”.
In Christian tradition, Gabriel is one of the three, four, or possibly seven, archangels and the primary messenger of God. He appears twice in the Old Testament and twice in the New Testament, but is best known for the Annunciation when he informs the Virgin Mary of Jesus’ impending birth.
He is only mentioned once in Good Omens: “‘Any more miracles and we’ll really start getting noticed by Up There,’ said Aziraphale. ‘If you really want Gabriel or someone wondering why forty policemen have gone to sleep–‘” (90).
From this one might infer that Heaven in general and/or Gabriel specifically keeps track of how many miracles are performed on the Earth.
The 2006 New Year’s Resolutions also mention Gabriel. Aziraphale’s Resolution #5 is, “I will try to be polite to Gabriel, no matter what the provocation.” This negative view of Gabriel may be influenced by Gaiman’s work on the Hellblazer series of graphic novels (Hellblazer #27). In that series, Gabriel is portrayed as pompous, prideful, cold, and bureaucratic. The main character of Hellblazer, John Constantine, often refers to Gabriel as “The Snob” and eventually orchestrates his Fall after Gabriel has another angel killed for fathering a child with a succubus.
“Gabriel.” Behind the Name. Accessed 24 May 2006. <http://www.behindthename.com/php/view.php?name=gabriel>.
“Gabriel.” The Catholic Encyclopedia. Accessed 24 May 2006. <http://www.newadvent.org/cathen/06330a.htm>.
“Gabriel.” Wikipedia. Accessed 24 May 2006. <http://en.wikipedia.org/wiki/Gabriel>.
“Hellblazer.” Wikipedia. Accessed 24 May 2006. <http://en.wikipedia.org/wiki/Hellblazer>.