#ergiscus

Triton - Son of Amphitrite and Poseidon - Poseidon’s messenger and herald

Benthesikyme - “Wave of the Deep” or “Lady of the deep swells” - Goddess of waves - Daughter of Amphitrite and Poseidon

Rhode - goddess and personification of the island of Rhodes. Wife of Helios.  Daughter of Amphitrite and Poseidon

Antaeus - Son of Poseidon and Gaea - Half Giant

(Heracles killing Antaeus)

Charybdis - daughter of Poseidon and Gaea (in some sources) she was a loyal child to Poseidon but since she kept covering land with water for him Zeus got mad and chained her to the sea floor, cursing her and turning her into a “bladder” and made her thirsty for seawater, which when she drank it, caused whirlpools. 

https://www.deviantart.com/c00lfr0g/art/Charybdis-388499917

Laestrygon - Son of Poseidon and Gaea, father of  Telepora (wife of Aeolus) possible parent/creator of the Laitsrygonians. 

Despoina - Daughter of Poseidon and Demeter - Goddess of Arcadian Mysteries/Veiled - born when poseidon went after demeter when both were horses.

Arion - Supernatural Horse (not sure if he’s a deity or just immortal creature) - Son of Demeter and Poseidon  born when poseidon went after demeter when both were horses.

Pegasus - immortal winged-horse, Son of Poseidon and Medusa (or just sprang from Medusa’s blood when Perseus beheaded her)

Chrysaor - Son of Poseidon and Medusa - "he who has a golden sword" - might be the father of Echidna

Herophile -Sea-nymph,  Daughter of Poseidon and Aphrodite, possibly a Delphic Sybil

Ergiscus - son of Poseidon and Aba (a naiad), the city of Ergisce in Istanbul was named after him. 

Aethusa - Daughter of Poseidon and Alcyone (a pleiad) - caught Apollo’s eye and had two kids with him Eleuther and Linus- ancestor of Orpheus.

Hyrieus - Son of Poseidon and Alcyone (a pleiad) - possible father of Orion, most account call him a king of various places. (Boeotia, Thrace or Chios)

Hyperenor - son of Poseidon and Alcyone

Hyperes - son of Poseidon and the Pleiad Alcyone He was the father of Arethusa, mother of Abas by Poseidon. Founded the city of Hyperea.

Anthas - Son of Poseidon and Alcyone, founder of Anthea

Abas - son of Poseidon and Arethusa (yes his own granddaughter).  Abas founded a tribe known as the Abantians or Abantes. He reigned over them as king. Possibly killed by his own grandson. 

Halirrhothius - Son of Poseidon and Euryte or Bathycleia. He was killed by Ares for raping his daughter Alcippe. 

Chrysomallos - Son of  Bisalpis or Bisaltis or Theophane - Golden winged ram, rescued some people, was them sacrificed to Zeus and skinned. 

Minyas - Son of Poseidon and somebody (there was a very long list of potential moms) a city founder. 

Lycus - son of Poseidon and Celaeno, one of the Pleiades. Together with his brother Eurypylus, they ruled over the Isles of the Fortunate which their father blessed.

Nycteus - (possibly a son of Poseidon and Somebody) - King of Thebes

Eurypylus - Son of Poseidon and Celaeno, either ruled over the isles of the blessed with lycus or was a king of cyrene

Asopus - possibly a son of Poseidon, a river deity

Parnassus - unkown

Eumolpus - possibly a son of Poseidon and Chione - King of Thrace

Phaeax - Son of Poseidon and Korkrya - from whom the Phaeacians derived their name.

Eirene - daughter of Poseidon and  Melantheia - gave her name to an island.

Amykos - Son of Poseidon and Melia - a king who would force people to box with them so he could kill them. Challenged the best of the Argonauts Polydueces, who killed him with a blow on the elbow. 

Mygdon - Son of Poseidon and Melia, also a king, killed by Heracles on his way to his ninth labour. 

Aspledon, a son of Poseidon and the nymph Mideia, a city in Boetia was named after him. 

Astacus - son of Poseidon and the nymph Olbia, eponymous founder of Astacus, Bithynia.

Leches  - son of Peirene and Poseidon, who was abducted by Poseidon. (squinty eyes at you mr. no-consent)

Evadne - daughter of Poseidon and Pitane who was raised by Aepytus of Arcadia. She fell in love with Apollo and of course got pregnant, the pregnancy was discovered by Aepytus, he was furious and left to consult the Oracle of Apollo. During the childbirth, Apollo sent Eileithyia and the Moirae to assist his lover and ease her pain. Evadne gave birth in the wilderness and left the child, Iamus, exposed to the elements. Five days later, Aepytus returned from the Delphi, where he had been told by Apollo's Oracle that Evadne's child was indeed the son of Apollo and destined to be a gifted prophet. He demanded that the child be brought to him, and so Evadne retrieved Iamus from the patch of violets where she had left him. Iamus had been nurtured for those five days by the honeybees that were sent by Apollo, or by the Fates. Evadne named the child Iamus (“Boy of the Violets”) He went on to found the Iamidae, a family of priests from Olympia.

Phocus - son of Poseidon and Pronoe

Ogyges - maybe a son of Poseidon or a Titan -  ruler in ancient Greece, generally of Boeotia, but an alternative tradition makes him the first king of Attica.

Achaeus was the son of Poseidon, the god of the sea and Larissa, daughter of Pelasgus, the son of Triopas, meaning he is of Argive descent through his mother's parentage. He is the brother of Phthius and Pelasgus.

Actor, the Epean son of Poseidon and Agamede, daughter of King Augeas. He was the brother of Belus and Dictys.

Bellerophon - was a divine Corinthian hero of Greek mythology, the son of Poseidon and Eurynome, and the foster son of Glaukos. He was "the greatest hero and slayer of monsters, alongside Cadmus and Perseus, before the days of Heracles". Among his greatest feats was killing the Chimera. Bellerophon was also known for capturing and taming the winged horse Pegasus with the help of Athena's charmed bridle, and earning the disfavour of the gods after attempting to ride Pegasus to Mount Olympus.

Eurypylus of Cos - was the son of Poseidon and Astypalaea or Mestra.He was the husband of Clytie and father of Chalciope, Chalcon and Antagoras.

Calaurus -  was the eponym of the island of Kalaureia near Troezen. He was the son of Poseidon

Delphus was said to be the son of Poseidon and Melantho, daughter of Deucalion (Though also could be the son of Apollo). He was from whom the town of Delphi was believed to have derived its name.

Elasippus, one of the ten sons of Poseidon and Cleito in Plato's myth of Atlantis. Elasippus, along with his nine siblings, became the heads of ten royal houses, each ruling a tenth portion of the island, according to a partition made by Poseidon himself, but all subject to the supreme dynasty of Atlas who was the eldest of the ten.

Geren was the eponym of the town of Geren in Lesbos. He was the son of Poseidon.

Hippothoon was the son of Poseidon and Alope, Cercyon's daughter. Hippothoon  is a figure in Greek mythology, often described as the King of Eleusis, succeeding to the throne after the death of Cercyon. He is the Attic hero and the eponym of the Athenian phyle called Hippothoontis. Although Cercyon had Alope buried alive, Poseidon turned her into the spring, Alope, near Eleusis. Hippothoon was stated to be present in the missions of Triptolemus and was mentioned along with Eumolpus as an Eleusinian hero who was worshiped according to honorary decrees dating to the 4th century BC. According to Pausanias, a heroon was dedicated to him for worship by hereditarily assigned priests.

Kymopoleia - was a daughter of sea god Poseidon and the wife of Briareus, one of the three Hundred-Handers.

Lamia  - was a daughter of Poseidon, and mother, by Zeus, of the Libyan Sibyl.It was perhaps this Lamia who, according to Stesichorus, was the mother of Scylla.

Megareus was king of Onchestus in Boeotia. In some myths, he was the eponymous king of Megara. Megareus was either son of Poseidon and Oenope, daughter of Epopeus, or of Onchestus (eponym of their kingdom),or of Apollo or of Aegeus,or of Hippomenes.

Nauplius,son of Poseidon by Amymone, daughter of Danaus. This Nauplius was reputed to have been the eponymous founder of Nauplia (modern Nafplion) in Argolis,and a famous navigator who discovered the constellation Ursa Major (Great Bear).

Palaestinus was a son of Poseidon and father of Haliacmon. From grief at the death of his son, Palaestinus threw himself into the river, which was called after him Palaestinus, and subsequently Strymon.

Sarpedon, a Thracian son of Poseidon, eponym of Cape Sarpedon near the outlet of the River Hebrus, and brother to Poltys, King of Aenus. Unlike the other two Sarpedons, this Thracian Sarpedon was not a hero, but an insolent individual who was shot to death by Heracles as the latter was sailing away from Aenus.