Jenny Quantum was born January 1, 2000 in Singapore, during the death of Jenny Sparks, where her birth mother was killed by super villains attempting to kidnap her and shape the coming century. Her biological father's identity and whereabouts are unknown. She was rescued and cared for by the Authority and later adopted by Apollo and Midnighter shortly after their marriage. She is the current leader of superhero team, The Authority.
Jenny was first named when she was kidnapped by the superteam known as the Americans(though a baby shown when Jenny Sparks died at the turn of the century is inferred to be her). Quantum is the corporeal spirit of the 21st century, and the youngest known Century Baby, as well as the reincarnation of the Spirit of the 20th Century, Jenny Sparks.
Quantum forced herself to age several years into her teens so that she could better fight the threat of Henry Bendix and his evil group. While fighting Bendix, Jenny was able to free the current Doctor, Habib Bin Hassan, and enlist him in the fight against Bendix.
When Captain Atom was trapped in the Wildstorm Universe, he accidentally killed Jenny Quantum after she'd tried to help him. This event, like so much else, was overwritten when Nikola Hanssen, the new Void, took control of her powers.
In the post-Worldstorm universe, Jenny Quantum, now renamed as Jenny Quarx, is the leader of the new Authority, which also appears to have the same line-up as the previous version. Quantum/Quarx is wearing a t-shirt with the Singaporean flag, in a manner reminiscent of Jenny Sparks' Union Jack t-shirts.
Number of the Beast and World's End
With the destruction of the earth heralded a resurrected John Cumberland (The High) of The Changers, Jenny sacrificed herself by using her body as a containment device to prevent the Carrier's engine, a caged miniature universe, from overwriting and destroying the universe when the damaged Carrier crashed to earth's London, England. Before absorbing the universe she kissed goodbye to The Doctor, telling him that should she return he should find her and tell her how it all turned out. What happened to Jenny after this is unknown as of yet.
- Spirit of the 21st Century: She was born "with the century" - on the stroke of midnight on New Year's Eve of 2000. Normally as a Century Baby grows they displayed certain superhuman abilities and skills, as well as immortality (not aging beyond her 20's until the century is over). In Jenny's case she displayed her powers a little after birth, whereas her previous incarnations only developed their abilities at 19. As with all Century Babies, it has been theorized that they act as an immune system for the planet; her very existence protecting Earth. As such she represents an aspect of the century into which she is born.
- Quantum Reality Manipulation: Jenny has the power to manipulate reality at the quantum level allowing her to achieve anything she can conceive of at the quantum molecular level. Jenny has the ability to manipulate the laws of quantum dynamics, manipulate ambient energies, and accelerate her own age. Her father Apollo once described her as having the ability to do "basically anything".
- Dimensional Travel
- Energy Projection: As a newborn she produced an energy blast of sufficient strength to disintegrate the legs of a giant who was attempting to kill her.
- Force Field
- Probability Manipulation
- Teleportation: She has the ability to teleport between points on Earth and also other dimensions.
- Immortality: She has stopped aging at nineteen and will most likely remain this way until her death. She is assumed to have at least a 100 year lifespan, not aging anymore at adulthood. Theoretically, she will live on through the next Spirit of the 21st Century.
- Vulnerability to Psionics: Telepathy is her only known true weakness, due to her being weak at blocking mind control.
- Spirit of the 21st Century: As with all century children that came before her, Jenny is pre-destined to die the moment the old century dies and the new one along with the next spirit is born.
- Jenny is actually 8-years old but has accelerated her age to that of a 14-year old.
- Jenny Quantum's lineage extends to the earliest accounts of human history, which include Jenny Stone and Jenny Fire, the first two "Century Spirits". Her direct ancestors before Jenny Sparks are Jenny Steam, Jenny Revolution, Jenny Plague and Jenny Inquisition.
- It has been suggested that, like Jenny Sparks, Jenny Quantum and the human race are linked for the current century and in Jenny Quantum's case, until the end of 2099. Meaning during a great depression, Jenny would be in a state of personal depression, though it is unknown if one causes the other or how. It has also been theorized that if she were raised with, for example, Nazi beliefs then humanity would fall under similar philosophies, though this has yet to be determined.
- Jenny has displayed the ability to summon alternate reality versions of herself from throughout the multiverse to aid her in conflicts. She can create imaginary universes at will, through this ability she created the universe known as Infinite City. 
- 84 Appearances of Jennifer Quarx (Wildstorm Universe)
- 15 Images featuring Jennifer Quarx (Wildstorm Universe)
- 5 Quotations by or about Jennifer Quarx (Wildstorm Universe)
- Character Gallery: Jennifer Quarx (Wildstorm Universe)