Justice Society Dark
The Justice Society Dark is a team of supernatural heroes within the DC Universe assembled to fight mystical threats that traditional heroes can't handle ordinarily. The team was lead by the original Mister Miracle (Thaddeus Brown) back in the Golden Age.
History
Mister Miracle assembled the Justice League Dark, a conclave of magic-users including Doctor Occult, Doctor Fate, the sorcerer Zatara, and the Blue Beetle. Facing a threat that would last decades, they used magic to permanently slow their own aging.
On January 10th 1941, Doctor Fate and his apprentice Salem the Witch Girl traveled to Slaughter Swamp in an effort to find the JSD to break Salem's curse. The JSD encountered Solomon Grundy.
The JSD were also involved in an event in 1945 called "The Storm of Sin" that a handful were aware of. It is unknown if JSD disbanded after Thaddeus Brown was plucked out of time. And it is also unknown if the Justice League Dark became the JSD's successor after they disbanded.