Jack the Ripper is an alias given to an unidentified serial killer active in the largely impoverished Whitechapel area and adjacent districts of London, England in the later half of 1888.
In the present day, headlines proclaim a cure for cancer. However, it also poisons the blood against vampires. Luring Andrew Bennett to a pyramid that housed magic rings, Mary uses them to travel back to 1888. Bennett follows and is mistaken for Jack the Ripper. Fleeing, but weak from not feeding, he collapses and is taken in by Dr. Kelsey and Kelsey's assistant, Penny Bower. Dr. Kelsey gave Bennett a transfusion of his own blood. The doctors saved Penny from a life of prostitution. Bennett assists Kelsey with his medical work. When a newspaper arrives with a sketch of his face under the headline "Ripper Strikes Again!", Kelsey plans to prove to Scotland Yard that Bennett is not the Ripper.
Bennett recalls the article about Allen Barr, the inventor of the cancer serum, who was described as "the eminent Dr. Barr is the son of a Soho mother who, in her younger days, narrowly escaped becoming the victim of Jack the Ripper." He deduces that Mary's plan is to kill Barr's ancestor, preventing the cancer cure.
He convinces Penny to help him find Mary. They do, at a place called "Taylor and Holmes" - Penny's sister, Lacey, is apparently dead on the ground, a victim of Mary, posing as the Ripper. Bennett confronts her, but, as she tries to make her escape, Kelsey grabs her arm, revealing himself as the Ripper. Mary manages to escape, but Kelsey accidently stabs himself to death struggling with Bennett (as he turns into a bat).
Two bobbies appear, one revealed to be Office Joseph Allen Barr, Penny's future husband, and ancestor of Dr. Barr.
It is believed that the man who earned the nickname "Jack the Ripper" was actually possessed by a demon named Calibraxis. Calibraxis also possessed an important member of the British royal family in the 1990s. 
Madame Xanadu visits Whitechapel during the Ripper killings and the Phantom Stanger eventually reveals why he must be allowed to kill. The Ripper's last victim, Mary Kelly, would have sired a son by Jason Blood who would have grown into a despot the likes humanity could not imagine.
The Ripper ran afoul of the Stranger and, terrified, fell into an open sewer to be, presumably, eaten by the rats.
It has been theorized that Vandal Savage may have either been Jack the Ripper or at the very least a close associate. Savage has claimed to have been many notable historical figures throughout his life, and his own testimony cannot always be considered reliable.  Another claimant to the role of Jack the Ripper is the delusional super-villain Red Jack. Red Jack is a known adversary of the Doom Patrol.
A version of Jack the Ripper appears in the Elseworlds story Batman: Gotham by Gaslight. In this reality, Jack the Ripper is actually Jacob Packer, a close friend of Bruce Wayne. Wayne is temporarily imprisoned for the Ripper's crimes, but later escapes and captures the real Jack the Ripper. Jacob was ultimately killed by James Gordon in self-defense when the killer tried to kill Bruce.
The entire British Royal family was wiped out in an explosion in the 19th century, except the Duke of Clarence, who is confined to a wheelchair, and a distant American cousin, Jack Planters, who becomes King. Planters is Jack the Ripper and under his rule the British Empire becomes steadily more misogynistic.
Jack was killed when the catatonic Duke of Clarence tackle him in his wheelchair sending Jack to fell on a dense bundle of stakes, impaling him to death.
- The real Jack the Ripper has been seen in various works of fiction, including those of DC Comics. However, he has not been depicted in a consistent manner - different writers use the character as they see fit, with little continuity between them.
- This character is a fictional representation of Jack the Ripper, a real person. More information on this person can be found at Wikipedia.org.
- Although this character was originally introduced during DC's Earth-One era of publication, their existence following the events of the 1985–86 limited series Crisis on Infinite Earths remains intact. However, some elements of the character's Pre-Crisis history may have been altered or removed for Post-Crisis New Earth continuity, and should be considered apocryphal.
- Red Jack, a supernatural entity who fought the Doom Patrol claimed that he was Jack the Ripper. Then again, he was also completely convinced that he had been God as well... not a very reliable character altogether, really.
- 9 Appearances of Jack the Ripper (New Earth)
- 3 Images featuring Jack the Ripper (New Earth)
- Quotations by or about Jack the Ripper (New Earth)
- Character Gallery: Jack the Ripper (New Earth)
- Jack the Ripper at dccomics.com
- Jack the Ripper at Wikipedia.org
- Jack the Ripper entry at Cosmic Teams
- wikipedia:Jack the Ripper at Wikipedia