Greek Gods Alphabetical order:  There were major Goddesses too. However my writing is exclusively on the male deities. I interpreted the title the Greek Gods literally as being on the male deities.    My sources are Edith Hamilton’s Mythology, Thomas Bulfinch’s Mythology, various books by Joseph Campbell Illustrated Book of Myths by Neil Phillip
Olympians.  These were the Deities that lived on Mount Olympus where life was without care, distress.  Everyone was blessed with Nectar and Ambrosia, the food of the Gods.
The home of the Olympians was Mount Olympus.  The mythic Mt. Olympus was seen as the home of the major ancint Greek deities.  There were two exceptions, Hades who ruled the underworld and Poseidan, whose realm was the oceans.
The ancient Greeks stated Thomas Bulfinch believed the earth was flat and Greece was the center of it.  This notion of a flat earth wasn’t disproven until the voyage of C. Columbus in the 1490s AD.  Mt. Olympus was in the middle of Greece.  So it was in the center of the center of the earth as was perceived by the Greeks of ancient times.  There were Goddesses who dwelled on the divine mountain. However my essay is on male deities only.  Apollo beautifully played his stringed instrument, the lyre for the rest of the Deities blissful entertainment.  Hephastus was responsible for the building of the Olympic palace, the armour, the chariots and most artistic endeavors.  He crafted the magic golden shoes that permitted the deities to move as speedily as the wind, or even thought. 
There were major differences between the deities of the Greeks of ancient times and how religionists of the monotheistic faiths view divinity.  One main distinction is most of the people who lived in acient times were polytheistic.  That is they believed in, worshiped many deities.  The cultures of Sumer, Akkad, Babylonia, Egypt, Assyria, Hitites, many others worshipped many divinities.  it was only ancient Israel and for a short time, Egypt who believed in one Deity.  Today the major monotheistic faiths are in chronological order, Judaism, Christianity and Islam. 
Plus the deities of olden times were perceived much differently.  They were seen as possessing rather human qualities such as falling love, desire, jealousy, having affairs. Certainly not most people today would think of as divine behavior.
Apollo aka Pheobus Apollo. Roman same name. Son of Zeus and Leto. He was most comely of the deities. Deity of healing , poetry, music and light. He was known for playing his stringed musical instrument, the lyre.  He was the God of archers too as well as a healer.  He was believed to have taught men the art of healing. Mainly he was the God of light.  As in the light of ilumination, enlightenment.  He was the embodiment of truth.His holy spring was Castalia.  His river Cephissus.  It was considered the center of the earth.He was a beneficial, kindly Deity.  A true love was Daphne who was turned into a laurel. She was according to Thomas Bulfinch, his first love.  He fell in love with her, through the malice of cupid and his magic arrow.  Apollo mocked Eros, aks Cupid and Aphrodite’s son punished him by making him fall for the beautiful Daphne. To make matters worse, he struck the Nymph with arrows to repel Apollo’s romatic passions. She was transformed into a laurel tree by her father, a river god, Peneus. Apollo as a tribute to her, made the Laurel, his official tree.  He crowned himself with laurel leaves in honor of her. The word laureate was named after the laurel. Many people think he was the deity of the sunThis is erroneous.  Helios was the sun deity. Helios was the child of Titan Hyperion. Holy to Apollo, crow, dolphin.
Conversely Apollo was the deity of the movement of the sun.  He figures in the myth of Phaeton.  His holy shrine was the Oracle of Delphi.  Where the future was supposedly foretoldby the priestesses there.  He was fathered by Zeus and the female Titan Leto.
Artemis (see Artemis) and Apollo were fraternal twins.  His son was Orpheus of Orpheus and Eurydice. Orpheus as considered the greatest musician of Greek mythology.   The french surrealist poet, film maker Orphee was based on Orpheus andEurydice.
Ares Deity of war and battles.  Roman-Mars. Offspring of Zeus and Hera.  Homer referred to him as “murderer,
bloodstained, the incarnate curse of mortals”…His sister Eris-discord. Her son strife.  War Goddess enyo, Latin Bellona.
This is where we get the word martial as in martial law. Mythologically he is best known as Aphrodite’s lover.
Son of Zeus and Hera (see Hera) He was eager for bloodshed.  He was detested by his fellow Olympians.
Only Aphrodite felt favorably toward him. In fact they were lovers, despite her marriage to Hephaestus.
Dionysus. Deity of wine.  Roman Bacchus.  Deity of wine, ecstasy.  Son of zeus and mortal Semele who could not withstand the grandeur of Zeus.  His followers were crazed. He was the lover of Ariadne who was so
cruelly abandoned by Theseus, after helping him, escape the Minatour, the half man, half bull, ferocious, bloodthirsty monster.
euphoric woman Maenads and his male follwer were Satyrs.  Satyrism is a medical term for a man who is oversexed.
Conversely because of the mellow pleasures of wine in moderation he was seen as the deity of civilization, law and peace.
Eros Roman Cupid. Deity of love.Son of Aphrodite, Goddess of love and beauty.   He struck arrows into people and made them fall in love. His great romantic love was Psyche.  Symbolically this is the marriage of love, eros and mind, psyche.  Psyche is where we
get the words psychic, psychology, psychiatry.  From Eros  we get erotic, erotica, emphasizing the sexual part of physical attraction.
Hades Deity of the Underworld. Roman name Pluto.  I think its very strange Disney would name one of his characters after the deity of the underworld.  Brother of Zeus.  Wife Persephone. He ruled  the other side of the rive Styx. Hades, the place of the underworld.  He was the  God of wealth, underground riches as well.  His cap or helmet made him invisible.  It was rare he left his realm.  He wasn’t
very welcomed in Olympus.  He was without pity.  He was terrible but not evil.  The Deity of passing was Thanatos. See below.
consisted of Tarturus, for the punishment of the sinful.  Elysian Fields for the virtuous. Charon was the one who rowed the boat that the deceased traveled on to their underworld.  Cerebus was the ferocious, lupine like three headed dog that guarded the path.
Hephaetus.  Deity of fire, the forge.  Some sources say son of Zeus and Hera. Other’s state only of Hera as  retribution of
Athena being borne of Zeus’s   Spouse was Aphrodite.  Mother Hero.  Father Zeus.  Disgusted by his homely looks, Zeus heaved him what would turn out to be a fall  lasted a full twenty four hours.  He heaved him from Olympus to land on Lemnos island.  One tale claims Zeus threw him out of Olympus because the Forge deity sided with Hera.  This source claims his crippled physique was the result of this fall and not because of how he was born. Thereby causing Hephaestus to become crippled.
Heracles, the supreme Greek hero Became a deity after his passing. Hercules in Roman.  He was included in Olympus and became one of the Olympians.
Hermes.  Deity of communications, messages, secrets, trade, wrestlers, other gymnastic sports. His father was Zeus. His mother was Maia. One of the many mortal female lovers of Zeus.  The word hermetic, meaning airtight enclosure is from Hermes.
Father Zeus, Mother the nymph Maia. Father Zeus.   Messenger of the ancient Greek deities.  Winged sandals on his feet,  a hat worn to make him invisible. The head covering consisted of a metal helmet  with  wings on each side.    From Hermes we get Hermetic, as it tightly sealed or hermetically sealed. He figures in the mythic wiseman Hermes Trismegistus, or Hermes three times great. Believed to my mythically related to the Egyptian Thoth, the ancient Egypt version of Hermes or Mercury in Roman mythology.
 His wand was the magical Caduceus. His father’s messenger. He was most skillfull, clever including being a thief. In Greek myth the day he was born he stole Apollo’s herds.  Zeus ordered. him to give them back to the deity.  He is mentioned in more Greek myths than any other deity.  He is the escort of souls departing to Hades.
He helped Persues slay Medusa the Gorgon by provding the hero with a mirror so he didn’t need to look at the face of Medusa.  She was so horrific any look, even a glimpse would immediately turn any onlooker to stone.
Zeus.  Supreme Deity of Greek mythology.  Husband of Hera. His brothers were Hades and Poseidan.  Lord of the Sky, Rain God, gatherer of Clouds. It was he who threw the thunderbolt.  Agamemnon, hero of the Iliad says of Zeus “Zues, most glorious, most great God of the st orm-cloud, thou that dwelest in the heavens.His breastplate was called the Aegis.  It was fearful to be beheld.  His bird, the eagle. Oracle Dodona in the land of Oaks. By the rustling of the oakleaves the priests made their interpretations.
Aquatic Deities besides Poseidan and Ocean.   Pontus was the deity of the  seas depths. His mother Earth. His father Nereus, a marine deity. He was known as “the Old Man of the Sea”   There is a story by Hemingway titled “The Old Man and the Sea”
Triton who blew the mighty trumpet of the seas.    Proteus. Some sources state he was Poseidan’s son. Others claim he attended to Poseidan’s needs.  Every source agreed he could change his shape at will.  There isProteus syndrome, very rare syndrome where parts of the body grew faster than others.  The result a very misshaped body. 
Aeolus.  Kind of the the winds.  Lived on earth.  Four main winds are Boras, North, Zephyr, West, Notus, South, Eurus, East. 
Charon. One of the underground deities of Hades. He was the one who ferried departed souls through the river Styx for a small fee.
Centaurs From the waist down, 
 Pan was a lesser earth Deity.  Father was Hermes.  He was part male human with a goat’s horn and hoofs.  He was believed by some religious scholars tobe the inspiration of the devil with its horns and cloven heels.  The Greeks saw him as deity of the forests, mountains.  They thought of him as  fun loving, somewhat rogish deity.  Certainly he was not considered malevolent.  He was a rather talented musician, especially playing his oral Pan pipes.His constant love for various nymphs were invaribably rejected because he was considered homely by them.  So much so that they panicked at his sight.  The word panic is derived from Pan.
Pontu: meaning Deep Sea, son of Mother Earth and whose father was Nereus, a sea deity who was much more prominant than his son.
Satyrs.  Resembled Pan in their looks and their realm.  The medical term Satyriasis, a male who is overly consumed with sexual feelings to the point of thinking of
nothing else comes from the word Satyr.
Sileni. Part men, part equine.  Walked upright on hooved feet and at times equine ears.  Invariably horse’s tails.  Commonly depicted on Greek pottery.
Silenus.  Some ancient sources claim he was Pan’s son. Others state he was his brother or Hermes’s son.  He was jolly corpulent eldery man.  He was a constant drunk.  So  much so
that he usually rode a donkey because he was too enibriated to travel otherwise. He knew well Bacchus and Pan.  He as the former’s tutor. Became a devoted devotee.
Sirens inhabited an unnamed island in the middle of the seas.  Their beautiful voices were a trap to ensure unsuspecting sailors to their doom.
They were a part of the Homer epic the Oddysey, the tale of Oddyseus, Roman Ulyseus and his travels.
Thanotos.  The deity of one’s passing.
Pre Olympians
Chronos or Saturn was a Titan giant who was the father of the chief male deity, Zues.
Rhea was a Titaness giantess who was the mother of Zeus. She was known as Ops too.  The Titans themselves were the offspring of
the earth and Heavens.  Both earth and the Heavens were derived from Chaos.  There were other Titans.
They were generally speaking known as the deities before the deities of Mt. Olympus.  One of these were Hyperion, the original solar deity.