Origin

Eclipso was the first incarnation of the Spirit of Vengeance, as revealed by The Phantom Stranger to then Reverend Richard Craemer. It was Eclipso who created the flood of Noah's time and was known for his ruthlessness, which quickly caused him to lose his station and become imprisoned in a black crystal forged in Apokolips by Darkseid. He has been known to play a game of chess every now and then against the dreded lord of Apokolips.

With the imprisonment of Eclipso, a new angel, Aztar, was turned into The Spectre--who Eclipso views as a usurper to his rank as the Spirit of Vengeance.

Hosts

As any spirit must be bound with a human host (as per the "new rules" following the crucifixion of Jesus), Eclipso too much be bound with a human to walk the Earth.

Bruce Gordon

His first host was a man named Bruce Gordon, a physicist specializing in solar energy, who was attacked by a sorcerer. Gordon became in possession of one of the black crystals that allows for Eclipso to maintain a host. In time, however, Eclipso's many crystals were forged into a single crystal--to prevent the spread of the spirit and the possession of multiple people.

Alex Montez

Alex managed to acquire the crystal as multiple small crystals, which he liquefied and injected into his bloodstream--save one which he use to summon the entity. The spirit of Eclipso was kept in check by the use of various tattoos. Alex worked with Black Adam, following Adam's expulsion from the JSA to keep some form of order.

Alex later killed himself following the breaking of one of his tattoos, to prevent Eclipso from controlling him.

Jean Loring

Following the events of Identity Crisis, Jean Loring was placed in Arkham Asylum where she was plagued by the voice of Eclipso. Eventually, Loring submitted to the voices and became the newest host for Eclipso. Loring-Eclipso was the driving force behind the events of Day of Vengeance, manipulating The Spectre into destroying many of the entities of magic. Eclipso is seen first talking to teh Spectre in his head until he makes her appear. Eclipso tells him that she was sunt to him from higher powers who want him to continue to do what he was doing. she tells him that he need to fight the source of evil which she tells him is magic. She is with Spectre when he is fighting Captain Marvel. While Spectre is fighting Shadowpact tries to dispose of her, but she puts up a fight. Eclipso gets back alive after Blue Devil pulls the trident from her body. She then grabs the weak Spectre and flies him away before anyone can see them. Eclipso comes with Spectre to fight Shadowpact. She fights them until Nightshade teleports her to the sun.

Loring also influenced heroes like Mary Marvel, causing them to be unnaturally wicked.

Loring and the entity eventually severed each other, leaving Loring to die.

Bruce Gordon, Once More

The Spectre, with the host Crispus Allen, found and used Bruce Gordon to bring about a new Eclipso, with him as the host. However, Eclipso has, at this time, been seen corrupting various heroes such as Plastic Man while also trying to be "tamed" by Gordon.