[The following is a small excerpt of a description of a Viking funeral that detailed human sacrifice as a part of the ritual. It was written by an envoy from the Caliph of Baghdad named Ibn Fadlan. His account was translated by A. S. Cook in 1923 and appeared in the Journal of English and German Philology. This funeral was for the chief of the Rus, who were the Viking settlers in Russia. It was performed on the Volga River in A. D. 922.]
Here she [one of ‘his girls [or] pages’] took off her two bracelets, and gave them to the old woman who was called the angel of death, and who was to murder her. She also drew off her two anklets, and passed them to the two serving-maids, who were the daughters of the so-called angel of death. Then they lifted her into the ship, but did not yet admit her to the tent. Now men came up with shields and staves, and handed her a cup of strong drink. This she took, sang over it, and emptied it. “With this,” so the interpreter told me, “she is taking leave of those who are dear to her.” Then another cup was handed her, which she also took, and began a lengthy song. The crone admonished her to drain the cup without lingering, and to enter the tent where her master lay. By this time, as it seemed to me, the girl had become dazed; she made as though she would enter the tent, and had brought her head forward between the tent and the ship, when the hag seized her by the head, and dragged her in.
At this moment the men began to beat upon their shields with the staves, in order to drown the noise of her outcries, which might have terrified the other girls, and deterred them from seeking death with their masters in the future. Then six men followed into the tent, and each and every one had carnal relationship with her. Then they laid her down by her master’s side, while two of the men seized her by the feet, and two by the hands. The old woman known as the angel of death now knotted a rope around her neck, and handed the ends to two of the men to pull. Then with a broad-bladed dagger she smote her between the ribs, and drew the blade forth, while the two men strangled her with the rope till she died.
Source:
Stephens, John Richard. “Eyewitness Reports.” Weird History 101: Tales of Intrigue, Mayhem, and Outrageous Behavior. New York: Barnes & Noble, 2006. 27, 29. Print.
Further Reading:
أحمد بن فضلان بن العباس بن راشد بن حماد (Ahmad ibn Fadlan)
I'm guessing this sort of thing played a part in inspiring satanic rituals in horror films.