Suspended Animation

Cryonics is the low-level temperature preservation of humans and animals in suspended animation by slowing their vital functions, for the purposes of preserving them and keeping them alive for extended periods of time.

Background
Before the Great War, several companies and government agencies are known to have produced cryonic technology. The technology varied significantly, from life preservation systems, containment devices, and weaponry such as cryo grenades and mines. In response, the public would remain skeptical of the technology and its safety.

Fallout 2
The United States Armed Forces experimented with cryonic technology, creating the systems at the Raven Rock facility, and using cryonic chambers in the Sierra Army Depot. One example is the cryonic submergence of PFC Dobbs in bio med gel. The Environmental Protection Agency made use of hibernation chambers, holding three subjects within each. These editions were large transparent tanks filled with ice-cold water, that is filled and drained through a long serpentine pipe system.

Fallout 3
The Enclave's scientific personnel at the Raven Rock base in the Capital Wasteland have several rooms dedicated to stasis, and their prisoner restraints use the same systems. There are two different versions of the Raven Rock stasis chambers: a green chamber holding the subject in the center, and a transparent blue holographic/light-based/photonic resonance chamber. The systems in Raven Rock appear to be the most advanced systems of their kind currently known on Earth. These chambers have been used to preserve yao guai, deathclaws, super mutants, feral ghouls, and human prisoners. Whether these stasis chambers are built for long-term preservation on the scale of years is unknown. The same blue-light stasis technology is used in Fort Constantine's T-51b power armor storage room. Weaponization for such creatures led to both invention and conflict, such as with the liquid nitrogen-based weapon the Cryolator. Vault 87 was equipped with four stasis chambers as standard issue.

Mothership Zeta
The alien civilization aboard Mothership Zeta made cryonics a core aspect of their invasion and their research. They worked by entirely sealing the subject and the chamber from the outside, and used freezing cold air to suspend the subject. When opening, the chamber would decompress and stabilize with outside air, and force the subject to drop to the floor. Furthermore, there was a second method of cryonics used by the aliens. In their dedicated cryo lab, during the Zeta Uprising, the Lone Wanderer could have frozen alien soldiers with the loose systems, thawing them into an ice block for a mere few seconds. Elliott Tercorien could have harnessed the energy to create cryo grenades and cryo mines, which cause the same effect on targets within the blast radius.

Fallout: New Vegas
Before the Great War, Robert House and his company, as well as the Big Mountain Research Facility, are known to have produced technology within the cryogenic and cryonic field. Robert House extensively researched extending human life and created his own cryonic chamber that allowed the user to connect their brain pattern and consciousness to an external interface.

The only instance of this technology in the Mojave Wasteland is House's cryonic preservation chamber in the Lucky 38. This is one of the only known instances of a cryonic chamber that links the subject's brain and consciousness with an external interface. It is an advanced piece of technology, linking Robert House to an external interface, from which he has access to large amounts of data from the Lucky 38's mainframe, as well as the ability to control his securitrons. Opening the chamber, even for a second, will doom the subject to having only little more than a year left at life due to exposure to outside contaminants.

Old World Blues
House hopes that with the Courier's help, he will be able to make the same cryonic technology he uses available to other high-value individuals in the future. The only other instance of cryonic technology is at the hazmat testing ground in the Big Empty, for storing the hazmat suit. Big Mountain also produced hibernation chambers with similar purposes.

Fallout 4
Vault 111, located in Boston, was built to observe the effects of suspended animation on unsuspecting test subjects for 180 days, and holds multiple cryosleep pods. They are first shown to the Sole Survivor pre-War, disguised as "decontamination" pods. The Sole Survivor was preserved for exactly 210 years, with their spouse and son being taken in the year 2227, 150 years in. All the other residents of the Vault perished by 2227, due to Conrad Kellogg not reactivating their life support, with Shaun being abducted as an infant by him for the Institute. Green stasis tanks are also seen holding super mutants in the FEV Lab in the Institute's BioScience sector.

In addition, a more experimental weapon was developed by the overseer of Vault 111, who made a prototypical rig that could propel super-chilled nitrogen gas at a target, slowly freezing them as they were exposed.

Fallout Tactics
Vault 0 kept pre-War geniuses in cryogenic stasis, by extracting their brains from their body and freezing them. They were then hooked up to the Calculator supercomputer, melding all of the identities of each connected brain into one. The vault also has a corresponding cryo lab to regulate these conditions.

Van Buren
The Boulder Dome in Denver was equipped with prototype military medical cryo tanks that had a very high malfunction rate, and before the Great War, scientists were frozen in sleeper tanks. Victor Presper continued to use the equipment during his time spent there. The Prisoner can wake them up by utilizing skill checks in Medicine and with the correct terminal.

Appearances
Cryonic technology appears in Fallout 2, Van Buren, Fallout 3, its add-on Mothership Zeta, Fallout: New Vegas and its add-on Old World Blues, Fallout 4, and Fallout Tactics. It is also mentioned in the Fallout: New Vegas add-on Dead Money.