From A Dictionary of Angels: Including the Fallen Angels by Gustav Davidson.
Sam(m)ael (Satanil, Samil, Satan, Seir, Salmael, etc.) -
a combination of "sam" meaning poison and "el" meaning angel. In rabbinic literature, Samael is chief of the Satans and the angel of death. In the Secrets of Enoch (Enoch II) he is the prince of demons and a magician. Samael has been regarded both evil and good; as one of the greatest and as one of the foulest spirits operating in Heaven, on earth, and in Hell. On the one hand he is said to be chief ruler of the 5th Heaven (in Jewish legendary lore his resitence is usually placed in the 7th Heaven), one of the 7 regents of the world served by 2 million angels; on the other hand, he is "that great serpent with 12 wings that draws after him, in his fall, the solar system." [Cf. Revelation 12.]
Samael is also the angel of death (one of a number of such angels) whom God sent to fetch the soul of Moses when the Lawgiver's days on earth had come to an end. Talmud Yalkut I, 110, speaks of Samael as Esau's guardian angel. Sotah 10b speaks of Samael as Edom's sar (angelic prince guardian). In the Sayings of Rabbi Eliezer, Samael is charged with being the one (in the guise of a serpent) who tempted Eve, seduced her, and became by her the father of Cain. In The Zohar (Vayishlah 170b), Samael is the dark angel who wrestled with Jacob at Peniel, although Michael, Uriel, Metatron, and others have been identified as this antagonist.
Samael is also equated with the satan (i.e., the adversary) who tempted David to number Israel [Rf. I Chronicles 21]. Targum Jonathan to the Prophets renders Genesis 3:6 as: "And the woman saw Samael the angel of death." This verse is translated in the Paraphrase of Job, 28:7, as: "the path of the Tree of Life which Samael, who flies like a bird, did not know, and which the eye of Eve did not perceive."
In Waite, The Holy Kabbalah, p. 255, Samael is characterized as the "severity of God" and is listed as 5th of the archangels of the world of Briah. Here he corresponds to the sefira Geburah.
Cornelius Agrippa, Three Books of Occult Philosophy, equates Samael with the Greek god Typhon.
Baruch III, 4, mentions "the angel Sammael."
In Charles, The Ascension of Isaiah IV, 7, occurs this passage: "And we ascended to the firmament, I and he [i.e., Isaiah and his escorting angel, a very glorious one, not named - but compare with the angel that Abraham encounters in the Apocalypse of Abraham], and there I saw Sammael and his hosts, and there was great fighting therein and the angels of Satan were envying one another." It is clear here that Sammael and Satan are interchangeable.
In Longfellow's extensive poem, The Golden Legend, when the rabbi asks Judas Iscariot why the dogs howl at night, the answer is: In the Rabbinical book it sayeth/ The dogs howl when, with icy breath,/ Great Sammael, the Angel of Death,/ Takes through the town his flight.
In fiction, "Red Samael the Seducer," father of the hero, is a character in Cabell, The Devil's Own Dear Son. Cabell calls Samael the "youngest and most virile of the 72 princes of Hell, a red-headed rogue who had made his reputation some centuries ago with both Eve and Lilith." To Cabell, Samael belongs to the order of seraphim and is "first of the art critics."