Beleth

A mighty and terrible king who rides a pale horse, like Death in the Book of Revelation.  He is named in the Welsh grimoire known as the Book of Incantations, where he is said to belong to the Order of Powers.  The sound of trumpets and other musical instruments marks his presence.  He is not an easy spirit to deal with, and the Book of Incantations cautions those summoning him to have a hazel stick and silver ring prepared ahead of time to help compel Beleth to obedience.  His main office concerns love between men and women, which he can inspire.  He rule either eighty-five or fifty-five legions.  The handwritten text is unclear.  See also BOOK OF INCANTATIONS.
THE DICTIONARY OF DEMONS, REVISED AND EXPANDED, M. BELANGER (2021)

A great and terrible king of Hell with eighty-five legions of spirits at his command.  He is said to belong to the angelic Order of Dominions, and to maintain hope that he will someday return to the seventh throne of heaven.  Wierus's Pseudomonarchia Daemonum renders his name Byleth.  According to both this text and Scot's Discoverie of Witchcraft, this demon can embroil people in foolish and misguided love, but he can be tricky to command.  When first summoned, he puts on a furious appearance to deceive the magician.  His appearance is heralded by trumpets and all manner of music, and Bileth himself manifests astride a pale horse.  The summoner is cautioned not to be intimidated by Bileth's initial manifestation, but instead to keep a hazel rod in one hand and force the demon to manifest more amiably in a special triangle constructed outside of the summoning circle.  If space does not allow for the construction of such a triangle, both the Pseudomonarcia Daemonumand Scot suggests placing a bowl of wine outside the circle to entice this spirit.  There is some danger in dealing with Bileth, and the magician is further cautioned to wear a silver ring on his middle finger of the left hand and to keep this pressed close against the face as a method of protection.  This method of protection is said to be used when summoning the demon Amaimon as well.  There is apparently some pay-off that makes all this trouble involving Bileth worth the effort.  In addition to procuring the love of others, Bileth is said to become a fast friend and obedient helper once he has been properly summoned and had his prideful ego appeased.  

Further in the Pseudomonarchia Daemonum, Bileth is credited with being connected to the first necromancer. According to this portion of the text, Noah's son Cham founded an art in the demon's name, and this art is decried as a wicked abomination by the author of Wierus's source text.  In the Pseudomonarchia Daemonum, the name is spelled alternatively as Byleth and Beleth.  Bileth is also named in connection with the legend of Solomon's Brazen Vessel.  He is said to have been the chief of the seventy-two infernal kings shut up in this vessel by the biblical Patriarch.  Under the name Belech, he appears as the thirteenth spirit in the Goetia.  In the Goetia of Dr. Rudd, he is said to be constrained by the angel Jazalel.  In the Liber de Angelis, this demon, under the name Bilet, is said to be a king of Hell.  He oversees a number of demons dedicated to suffering and disease.  In the Book of Oberon, Bileth is one of the twelve principal spirits serving Amaimon, king of the south.  The text states that he turns people invisible and possesses the power to bless or curse items.  

He also appears in several spells recorded in the Munich Handbook.  He is found in the Sworn Book of Honorius as a minister of the demon-king Harthan.  In Driscoll's edition of this work, Bileth is associated with the element water.  In the Peterson translation of this work, he is instead connected with the spirits of the moon.  Other variations of his name include Beleth, Byleth, and Bilet.  See also AMAIMON, BOOK OF OBERON, GOETIA, HARTHAN, LIBER BE ANGELIS, MUNICH HANDBOOK, RUDD, SCOT, SWORN BOOK, WIERUS.
THE DICTIONARY OF DEMONS, REVISED AND EXPANDED, M. BELANGER (2021)