(sorry if this isn't in the right place)
Aamon or Amon (Christian demonology)
Abaddon/Apollyon (Christian demonology)
Abalam (Christian demonology)
Abezethibou (Testament of Solomon)
Abraxas (Gnosticism)
Abyzou (Jewish mythology)
Adramelech (Assyrian mythology, Christian demonology)
Aeshma (Zoroastrianism)
Agaliarept (Jewish mythology)
Agrat Bat Mahlat (Jewish demonology)
Agares (Christian demonology)
Agiel (Jewish mythology)
Ahriman/Angra Mainyu (Zoroastrianism)
Aim/Haborym (Christian demonology)
Aka Manah/Akem Manah/Akoman/Akvan (Zoroastrianism)
Ala (Slavic mythology)
Alal (Chaldean mythology)
Alastor (Christian demonology)
Alloces/Allocer (Christian demonology)
Allu (Akkadian mythology)
Amaymon (Christian demonology)
Amdusias (Christian demonology)
Ammut (Egyptian mythology)
Amon (Christian demonology)
Amy (Christian demonology)
Anamalech (Assyrian mythology)
Andhaka (Hindu mythology)
Andras (Christian demonology)
Andrealphus (Christian demonology)
Andromalius (Christian demonology)
Anzu (Sumerian mythology)
Apep (a.k.a. Apophis) (Egyptian mythology)
Armaros (Jewish demonology)
Archon (Gnosticism)
Asag (Sumerian demonology)
Asakku (Babylonian mythology)
Asb'el (Jewish mythology)
Asmodai/Asmodeus (Jewish folklore and Christian mythology)
Astaroth (Christian demonology)
Asura (Hindu mythology)
Azazel / Azaz'el (Jewish demonology)
Azi Dahaka/Dahak (Zoroastrianism)
Baal/Bael (Christian demonology)
Balam (Christian demonology)
Balberith (Jewish demonology)
Bali Raj (Hindu mythology)
Baphomet (Christian folklore)
Barbas (Christian demonology)
Barbatos (Christian demonology)
Bathin/Mathim/Bathym/Marthim (Christian demonology)
Beball (Christian demonology)
Beelzebub (Jewish demonology, Christian demonology)
Behemoth (Jewish demonology)
Belial (Jewish demonology, Christian demonology)
Beleth (Christian demonology)
Belphegor (Christian demonology)
Berith/Beherit (Phoenician mythology, Christian demonology)
Bhūta (Sanskrit)
Bies (Slavic mythology)
Bifrons (Christian demonology)
Boruta (Slavic mythology)
Botis (Christian demonology)
Buer (Christian demonology)
Bukavac (Slavic mythology)
Bune (Christian mythology)
Bushyasta (Zoroastrianism)
Caim/Camio (Christian demonology)
Carabia (Christian demonology)
Charun (Etruscan mythology)
Chemosh (Moabite mythology)
Choronzon (Thelema)
Cimejes/Kimaris/Cimeies (Christian demonology)
Corson (Christian demonology)
Crocell/Procell (Christian demonology)
Culsu (Etruscan mythology)
Daeva (Zoroastrianism demonology)
Dagon (Semitic mythology)
Dantalion (Christian demonology)
Danjal (Jewish mythology)
Dasa (Hindu mythology)
Davy Jones (nautical folklore)
Decarabia (Christian demonology)
Demiurge (Gnosticism)
Demogorgon (Christian demonology)
Devil, the (Christian demonology)
Div-e Sepid (Persian mythology)
Drekavac (Slavic mythology)
Dzoavits (Native American mythology)
Eligos (Christian demonology)
Eisheth (Jewish demonology)
Empusa (Greek mythology)
Eblis (Islamic demonology)
Focalor (Christian demonology)
Foras/Forcas/Forras/ (Christian demonology)
Forneus (Christian demonology)
Furcas/Forcas (Christian demonology)
Furfur (Christian demonology)
Gaap (Christian demonology)
Gader'el (Jewish demonology)
Gaki (Japanese mythology)
Gamigin (Christian demonology)
Gello (Greek mythology, Christian mythology)
Glasya-Labolas/Caacrinolaas/Caassimolar/Classyalabolas/Glassia-labolis (Christian demonology)
Gremory/Gomory (Christian demonology)
Grigori (Jewish demonology)
Gualichu (Mapuche mythology)
Guayota (Guanche mythology)
Gusion/Gusoin/Gusoyn (Christian demonology)
Haagenti (Christian demonology)
Halphas/Malthus (Christian demonology)
Haures/Flauros/Flavros/Hauras/Havres (Christian demonology)
Humbaba (Sumerian mythology, Akkadian mythology)
Ifrit (Islamic mythology)
Imp (Christian demonology, Germanic folklore)
Incubus (Christian demonology, Chaldean mythology, Jewish folklore)
Ipos/Ipes (Christian demonology)
Iblis (Islamic demonology)(Satan)
Jikininki (Japanese mythology)
Kabandha/Kabhanda (Hinduism)
Kasadya (Jewish demonology)
Kokb'ael (Jewish demonology)
Kali (Hindu mythology)
Kroni (Ayyavazhi demonology)
Labal (Christian demonology)
Labasu (Babylonian mythology)
Lady Midday (Slavic mythology)
Lamashtu (Sumerian mythology)
Lamia (Bulgarian folklore, Christian demonology and Greek mythology)
Latiangle (Christian demonology)
Legion (Christian demonology)
Lechies (Slavic mythology)
Leyak (Indonesian mythology)
Lempo (Finnish mythology)
Leraje/Leraie (Christian demonology)
Leviathan (Jewish demonology, Christian demonology)
Lili/Lilin/Lilim (Jewish demonology)
Lilith (Sumerian mythology, Akkadian mythology, Jewish folklore)
Lucifer (Christian demonology, originated in Greek myth)
Lucifuge Rofocale (Christian demonology)
Malphas (Christian demonology)
Mammon (Christian demonology)
Mara (Buddhist mythology)
Maricha(Hindu mythology)
Marax/Morax/Foraii (Christian demonology)
Marbas (Christian demonology)
Marchosias (Christian demonology)
Masih ad-Dajjal/Ad-Dajjal/Dajjal (Islamic eschatology)
Mastema (Jewish demonology)
Medusa (Greek mythology)
Melchiresa / Melki-resha (Jewish mythology)
Mephistopheles (Christian folklore, German folklore)
Merihem (Christian demonology)
Moloch (Christian demonology)
Murmur (Christian demonology)
Naamah (demon) (Jewish demonology)
Naberius/Cerbere (Christian demonology)
Naberus (Christian demonology)
Naphula (Christian demonology)
Neqa'el
Ninurta (Sumerian mythology, Akkadian mythology)
Namtar (Sumerian mythology
Onoskelis (Testament of Solomon)
Oray (Christian demonology)
Orcus
Orias (Christian demonology)
Oriax (Christian demonology)
Ornias (Testament of Solomon)
Orobas (Christian demonology)
Orobos (Christian demonology)
Ose (Christian demonology)
Paimon (Christian demonology)
Paimonia (Christian demonology)
Paymon (Christian demonology)
Pazuzu (Akkadian mythology, Sumerian mythology)
Phenex (Christian demonology)
Pinem'e
Pithius (Christian demonology)
Pruflas (Christian demonology)
Pruslas (Christian demonology)
Puloman (Hindu demonology)
Purson/Curson (Christian demonology)
Rahab (Jewish folklore)
Raim (Christian demonology)
Raum (Christian demonology)
Ronove (Christian demonology)
Ronwe (Christian demonology)
Rum'el
Rumyal
Rusalka (Slavic mythology)
Rakshasa (Hinduism)
Rangda (Hinduism)
Ravan (Hinduism)
Sabnock (Christian demonology)
Saleos (Christian demonology)
Samael (Jewish demonology)
Satan (Jewish demonology, Christian demonology, Islamic demonology)
Scox (Christian demonology)
Seir (Christian demonology)
Semyaz (Jewish demonology)
Serguthy (Haitian demonology)
Shax/Chax (Christian demonology)
Shedim (Jewish folklore)
Sidragasum (Christian demonology)
Sitri (Christian demonology)
Sthenno (Greek mythology)
Stolas (Christian demonology)
Succubus (Sumerian mythology, Akkadian mythology, Jewish folklore, Christian demonology)
Surgat (Christian demonology)
Tannin (Jewish demonology)
Ukobach (Christian demonology)
Uvall (Christian demonology)
Valac (Christian demonology)
Valefar/Malaphar/Malephar (Christian demonology)
Vapula (Christian demonology)
Vassago (Christian demonology)
Vepar (Christian demonology)
Vephar (Christian demonology)
Vine (Christian demonology)
Xaphan (Christian demonology)
Xezbeth (demonology)
Yeqon
Yeter'el
Zagan (Christian demonology)
Zepar (Christian demonology)
Ziminiar (Christian demonology)
(I didn't compile this list, though I have added to it)