- "This "stone", were there deep cavities carved into it?"
The Monolith was one of many products produced by the Kree during the creation of the Inhumans on prehistoric Earth. The ruling Kree hierarchy, deeming the creation of the Inhumans by a rogue Kree faction as being a mistake, conceived the Monolith as a means of wiping them out. Aside from destroying the Inhumans, the Monolith also had the ability to absorb and then transport individuals across space.
An Inhuman of immense power was born and desired to rule the Earth. He was banished by others through the Monolith to Maveth. The Inhuman's followers later formed a secret society with the goal to bring their leader back to Earth and gained possession of the Monolith. Over the centuries the society became known as HYDRA. At some point, the leaders of HYDRA decided to extract five smaller stones from the Monolith. These were eventually divided evenly among HYDRA's most powerful leaders.
Over the course of history, the Monolith changed hands a lot. It was owned by Germanic tribes, spent the Hundred Years' War in France, and before the Napoleon era, it was moved to England. In 1839 the Monolith was kept in a castle in Gloucestershire. A group of noblemen, members of the HYDRA society, used the Monolith to send various people to the other side of the portal, but none of them ever came back.
The Monolith was later found on an excavation site in Yucatán during the late 1800s or early 1900s. By 1970 the artifact was known to be in the possession of HYDRA cultists whose members included the Malick family, used again in their regular sacrificial rituals to the Inhuman on the other side. 
In 2001, the Monolith was in the possession of NASA which sent a four man expedition into its portal to survey the planet on the other side. Will Daniels went with three scientists; it was his job to protect them from danger until they could be retrieved. However, the whole expedition was secretly orchestrated by Gideon Malick's HYDRA branch as part of Project Distant Star Return with which Malick hoped to bring HYDRA's ancient Inhuman leader back to Earth. When the expedition did not return, the Monolith was given to S.H.I.E.L.D. and was stored in the cargo hold of the aircraft carrier Iliad.
Director Nick Fury ordered Bobbi Morse to destroy the Iliad to assure that the Monolith would not fall to HYDRA during the HYDRA Uprising. Morse ultimately defied her orders, saving the ship, and continuing the existence of the Stone.
Raina had a precognitive dream about the Monolith, and this information was passed on to Afterlife leader Jiaying, who allowed Raina and Gordon to infiltrate the vessel to verify its location. When the two were discovered by Lance Hunter, Raina and Gordon escaped and the Monolith was given an armed regiment to defend it.
During the Inhuman War against S.H.I.E.L.D., the first place that the Inhumans attacked on the Iliad was the room that housed the Monolith. After taking control of the room, and later the ship, Gordon and Lincoln Campbell observed the Monolith; Gordon assured Campbell that it would not be used against them with the ship now conquered.
After the Iliad was retaken by S.H.I.E.L.D., the Monolith was moved to the Playground. Jemma Simmons tried requesting permission from Alphonso Mackenzie, who had been put in charge of all extraterrestrial artifacts, to send a probe into the box to examine the Monolith but Mackenzie declared that they will never open the box.
While Leo Fitz awkwardly tried to ask Simmons out to dinner, he stumbled, causing the lock on the case to loosen. Simmons then found out that the case was unlocked; when trying to re-lock the case, the stone morphed into its liquid form, shooting out and swallowing her. It transported her to another world, then went back to its original form.
- "And now I think... I know it's a black hole. It's dark matter made solid. It can warp space-time."
- ―Leo Fitz about the Monolith
Frustrated after months of research and having come up with no results other than the conclusion that Jemma Simmons had been killed, Leo Fitz took a shotgun and blasted the lock off the container of the Monolith. He then stepped inside the container and began punching and kicking it, begging it to "do something"; it remained solid and dormant.
Used One Last Time
Just as the other agents pulled Leo Fitz away from the Monolith and closed the door, it transformed to its liquid state. When it returned to solid, it had left sand on Fitz's face and the floor. Analyzing it, Fitz determined that the sand didn't originate from Earth and realized the Monolith's function as an interstellar portal. Recognizing the need for an alien in the hopes of understanding the portal, Coulson recruited the Asgardian Elliot Randolph. Randolph only agreed to come to the Playground to confirm the portal's existence and destroy it. Upon seeing the Monolith's random transformation, he guessed that it reacts to another planet. He agreed to help S.H.I.E.L.D. rescue Simmons in exchange for destroying the portal afterwards.
Alphonso Mackenzie later loaded the Monolith into the Zephyr One and delivered it to a castle in England. There the rock was placed in a containment unit that forced it to open a portal. While the portal was open, Fitz fired a flare to Maveth. Suddenly the machines fell apart and the stone returned to its solid state.
Later, Daisy Johnson used her vibrational powers to open the portal. Fitz entered, tied to a tether. The machinery of the tether began to collapse; Bobbi Morse and Mackenzie tried to sustain it while Johnson was straining to hold the portal open. The rock could no longer maintain its integrity and disintegrated; Fitz and Jemma Simmons were back on Earth.
Fragments of the Monolith were brought back to the Playground; Simmons saw the pieces as she took a tour of her laboratory. Sometime later, Simmons returned to the lab and inspected the fragments. Morse entered and assured Simmons that the pieces were now inert.
After the War on HYDRA, HYDRA's leader Gideon Malick started collecting the five fragments of the Monolith so he could finish Project Distant Star Return. The task was easy for him because most of HYDRA's heads were dead, and the remaining ones were being hunted by Grant Ward who was aiming to remake the organization in his own image. One of the fragments of the Monolith was kept in Wolfgang von Strucker's secret vault in Zepkow, Germany, which was procured by Malick six months after Strucker's death. While Malick visited the vault, Grant Ward entered; Malick showed Ward the contained fragment and asked him to watch as it transformed between its solid and liquid states, as he told Ward the story of Hive, his banishment to Maveth, and the true origin and purpose of HYDRA.
Return of Hive
In order to bring Hive back to Earth, Gideon Malick, who possessed all five fragments, used a device that turned the fragments into the portal automatically. The device was put in a chamber in the HYDRA Castle. With the help of Jemma Simmons' calculations, HYDRA knew exactly when the portal would reopen. Grant Ward, Leo Fitz and a team entered through the portal to Maveth to search for Hive. Before Malick ordered his men to close the portal, Phil Coulson jumped from a Quinjet through the portal, seeking revenge after Ward. After a few hours, S.H.I.E.L.D. managed to take control on the portal chamber. Simmons told the group about HYDRA' goal to bring Hive back. Lincoln Campbell believed that the portal had to be destroyed. Acting Director, Alphonso Mackenzie, decided that he and Daisy Johnson would stay to make sure Coulson and Fitz would come back. After the two returned, Mackenzie ordered Melinda May on Zephyr One to destroy the castle, with the fragments with it. However, Hive managed to return to Earth through the portal, using Ward's body as a host.
|Appearances for the Monolith|
In chronological order:
Behind the Scenes
- Prior to the release of Season Three, Executive Producer Jeffrey Bell refered to the Monolith as "the portal" in an interview.
- ↑ 1.0 1.1 1.2 1.3 Agents of S.H.I.E.L.D.: 2.20: Scars
- ↑ 2.0 2.1 2.2 Agents of S.H.I.E.L.D.: 3.08: Many Heads, One Tale
- ↑ 3.0 3.1 3.2 Agents of S.H.I.E.L.D.: 3.09: Closure
- ↑ 4.0 4.1 Agents of S.H.I.E.L.D.: 3.02: Purpose in the Machine
- ↑ 5.0 5.1 Agents of S.H.I.E.L.D.: 3.01: Laws of Nature
- ↑ Agents of S.H.I.E.L.D.: 3.16: Paradise Lost
- ↑ Agents of S.H.I.E.L.D.: 3.05: 4,722 Hours
- ↑ Agents of S.H.I.E.L.D.: 2.15: One Door Closes
- ↑ Agents of S.H.I.E.L.D.: 2.19: The Dirty Half Dozen
- ↑ Agents of S.H.I.E.L.D.: 2.21: S.O.S. Part One
- ↑ 11.0 11.1 Agents of S.H.I.E.L.D.: 2.22: S.O.S. Part Two
- ↑ Agents of S.H.I.E.L.D.: 3.03: A Wanted (Inhu)man
- ↑ Agents of S.H.I.E.L.D.: 3.10: Maveth
- ↑ Marvel’s Agents of S.H.I.E.L.D.'s Executive Producer Jeff Bell on What to Expect In Season Three and Beyond