Parallel World

In JoJo's Bizarre Adventure, the existence of Parallel worlds, Alternate universes, realities or dimensions is a recurring concept. It is mainly conceptualized as the premise behind certain Stand abilities.

Steel Ball Run
In Steel Ball Run, there is a limitless number of Parallel worlds that a follow a near identical pattern of events. In the "Base World" there exits the Saint's Corpse that is scattered across The United States Of America, This would lead to a Horse Race around the country two thousand years later for the secretive purpose of collecting all this corpse. The very same Horse Race exits within other the parallel worlds but instead of the Saints corpse, other items take its place in value, such as diamonds that are held by President Funny Valentine's.

Funny Valentine's Stand, Dirty Deeds Done Dirt Cheap, allows different parallel worlds/dimensions to overlap at the same time and/or in the same place, allowing people and objects to travel between them by preserving their internal gravity. .To achieve this, Valentine must compress the target between two objects, which can include anything from doors and drawers to spilled water (as seen in ). However, in the realm of parallel worlds, only a single instance of any person or thing can coexist. If two or more entities come into existence, they will gradually be drawn toward each other until a collision occurs, resulting in their simultaneous erasure (as elaborated in ). Ultimately, Valentine is overcome by the effects of Tusk ACT4, known for its infinite rotation, which directly manipulates Valentine's gravitational forces. Nevertheless, he still manages to summon Diego Brando (THE WORLD) to the base world as a final resort in order to obtain the the corpse for America's benefit.

Cream and The Hand
Vanilla Ice's Stand, Cream is able to devour itself and its user to become a void that devours everything it comes in contact with. Vanilla describes it as a dimension of darkness, though he is unsure himself where exactly the objects are sent to. While in this dimension, Vanilla and his Stand are invulnerable to attacks. Okuyasu Nijimura's The Hand is similar to Cream, able to erase whatever space its right hand touches. Okuyasu states that not even he knows where the voided objects go, but it seems the objects are eliminated like an extremely sharp blade had sliced clean through them. This ability allows the normally short-range Stand extreme distance in its attacks, as it can simply remove the space between itself and a target to bring them within range.

Atom Heart Father
Yoshihiro Kira possesses the extraordinary ability to fashion a pocket dimension within any photograph captured by his camera. Within this photograph, any actions undertaken manifest in the actual world. Moreover, the space depicted in the photograph is isolated from the real world: individuals attempting entry find themselves on the other side, while those within are unable to escape (as detailed in ). By ensnaring himself within these photographs, Yoshihiro persists as a spectral entity even after his demise (as evidenced in ).

Man in the Mirror
Illuso wields the Stand known as "Man in the Mirror." This Stand grants him the power to forge an alternate realm discernible through reflective surfaces. Within this realm, Illuso can freely transport parts of himself or others. Notably, the Man in the Mirror's world exists not as a physical realm but as a dimension forged from spiritual energy. Consequently, only the spiritual aspects of those drawn into this mirror dimension materialize within it (as explained in ). Moreover, these individuals return to the real world upon Illuso's demise (as delineated in ).

Made in Heaven
After awakening the formidable Stand, Made in Heaven, Enrico Pucci harnesses its extraordinary power to accelerate the passage of time for all living beings. This acceleration paves the way for the survivors amidst the ensuing chaos to transcend into the next iteration of the same universe (as recounted in ). Within this accelerated timeframe, living beings undergo an experience wherein they traverse the entirety of their future events as they unfold. These profound experiences become etched into their very souls, resulting in premonitions of forthcoming events. Pucci's aspiration is that these premonitions will guide them towards a state of happiness (as elucidated in ). For those unfortunate souls who do not endure the transition, they are substituted by counterparts who bear striking resemblances in both appearance and personality. These replacements assume identical roles in the grand tapestry of Fate (as further explored in ).

Wired
The hooks and cables stored inside Pork Pie Hat Kid's mouth are said to go through dimensions when Pork Pie Hat Kid sends them into a bowl of water. The hooks then spring from this dimension into the original dimension through the bottom of any object or organism, for example: a bird feather or a beetle.

37th Universe
Though most of the novel takes place in the original universe, the other half of JORGE JOESTAR takes place in the 37th universe; after the effects of Made In Heaven resetting the world thirty-six times, it creates a 37th universe. It is where the main protagonist, Joji Joestar—the alternate of the other main protagonist, George Joestar II, goes on his adventure to solve the murder of the detectives in Morioh. The 37th universe has characters from the original universe, like in Part 4, 5, and 6. Most of them have slightly different names, and different Stands. Because of Made In Heaven's effects, thirty-seven universes were created. Only a few are mentioned, like the second universe (also known as the Steel Ball Run universe), the unknown universe where a version of Funny Valentine originates from, and the 37th universe where the other side of the novel is set in with Joji. He is accompanied by a man named Kars from that universe, who leads the other 36 versions of himself in order to return back to earth from his eternal banishment during the time placement in Battle Tendency.

Unknown Universe
During the final chapters of the novel, another Funny Valentine meets Joji and assists him in defeating Dio Brando. His universe of origin is unknown, though it is said he is in a universe between the 2nd and 37th universes.

Cube and Arrow Cross House
In JORGE JOESTAR, Reimi Sugimoto is alive, and is a Stand User. Her Stand,, is a die-shaped facsimile of her childhood home, which functions as a time traveling tesseract allowing Reimi and anyone she entrusts to travel to different universes and time periods. She also has an ability named Cube House, which is built inside of the Arrow Cross House. It only allows one person inside, any more leads to contradictions, which ends up sending one of the persons into an empty universe with no escape in order to make space.