This article contains spoilers for Eternals #1 by Kieron Gillen and Esad Ribic.
Marvel's Eternals are better at cheating death than even the X-Men. Comics have never exactly had a reputation for taking death particularly seriously, so much so that the phrase "comic book death" is now taken to refer to a throwaway death done for shock purposes that will swiftly be reversed. The X-Men comics in particular have a reputation for treating death as a revolving door, so much so that some characters' resurrections were never even explained.
When superstar writer Jonathan Hickman relaunched the X-Men franchise in 2019, he decided to subvert this by codifying death and resurrection. The X-Men learned how to synergize mutant powers and Cerebro technology to successfully resurrect the dead, and they set about reversing the deaths of millions of mutants over the decades. So long as the Resurrection Protocols are in effect, the mutants of Earth are now functionally immortal. The X-Men now consider death little more than a temporary inconvenience, so much so that Professor X even orchestrated his own assassination. But, as ground-breaking as the Resurrection Protocols may be, Kieron Gillen and Esad Ribic's Eternals reveals the X-Men are amateurs in this field.
Marvel Comics killed the Eternals in July 2018, in a strange scene that suggested they killed one another in a fit of madness after discovering they had been manipulated by the Celestials. Gillen and Ribic's Eternals #1 begins with their resurrection, revealing the Eternals are bound to a "Machine" created by the Celestials that resurrects them when they die. The Machine stores multiple backups, and in the event an Eternal has proved dangerous it resurrects them to their safest stored backup. That's used in Eternals #1 to rehabilitate Sprite, an Eternal who had previously gone rogue.
The process is fascinating, and it's remarkably similar to the X-Men's Resurrection Protocols. There are, however, two major differences. The first is that the X-Men are dependent on a combination of mutant powers and Cerebro technology, while the Eternals are apparently dependent on a single Machine. The second, of course, is that the Eternals have been dying and resurrecting for longer than mutants have walked the Earth.
It's interesting to note the X-Men's Resurrection Protocols have had an unprecedented cosmic effect, with the return of millions of mutants almost killing Death in the Marvel Universe. Presumably, the reason the Eternals haven't caused similar problems is that there are only a hundred of them, meaning the impact on the balance of life and death is far less significant. It remains to be seen whether that limitation is the reason this is sustainable - and whether the X-Men's Resurrection Protocols will have more effects down the line due to the scale of their process.