Warning: This article contains spoilers for The Witcher: Nightmare of the Wolf.

Nearly 30 years pass between the first and final episodes of The Witcher Season 1, yet the show’s titular monster hunter, Geralt of Rivia, seems to have hardly aged a day during that time. What’s the secret to his lasting looks and longevity? Well, to answer that question, we’ll have to discuss how witchers are made.

In The Witcher book series by Andrzej Sapkowski, a group of mages — humans capable of harnessing the power of Chaos to break the laws of physics — create the first witchers, using alchemy to turn ordinary people into weapons capable of fighting the monsters menacing the Continent. Only three or four out of every 10 children who undergo the excruciating magical procedure known as the Trial of the Grasses survive, but those who do are bestowed with numerous powers to help them face such deadly creatures as the sharp-fanged flying basilisk to the cursed, organ-eating striga. Witchers have enhanced strength and reflexes, heightened senses and can recover from all but the most dire of wounds. They also have a greatly extended life span.

Vesemir, the oldest known living witcher, was born in 1095, according to the human calendar of the Continent. In the 2021 Netflix animated film The Witcher: Nightmare of the Wolf, a young Vesemir abandons his life as a servant to help the witcher Deglan save his mistress from being possessed by a monster. Enticed by the promise of adventure and the ability to earn gold for himself, Vesemir chooses to follow in Deglan’s footsteps and join the witchers of the School of the Wolf at the age of 12. He travels to the witcher stronghold of Kaer Morhen where he received intense combat training to prepare him for his new line of work. The School of the Wolf has a brutal initiation ritual known as the Red Swamp Gauntlet where initiates are left in a monster-infested swamp and must find their way home to the witcher stronghold of Kaer Morhen. Those who survive undergo the Trial of the Grasses, where they face hallucinations and agonizing physical pain. Most die within days.

Yet those who endure gain significant benefits. Vesemir is already nearly 70 when Kaer Morhen falls in 1165 at the end of Nightmare of the Wolf, but he still appears to be a young man in his prime. His long life has helped the School of the Wolf endure, allowing him to take care of and train the other young survivors who were hidden when the citadel was assaulted by mages, monsters and humans seeking to destroy the witchers. A five-year-old Geralt was one of those young initiates, having just endured the Trial of the Grasses.

By the time Geralt appears in the first episode of the Netflix series The Witcher, he is already 71, though he is played by 36-year-old Henry Cavill. Aside from his catlike eyes, white hair and world-weary attitude, Geralt doesn’t really show his age. By the start of the second season, Geralt is 104 and Vesemir is 169. Geralt’s mentor and adoptive father is played by Kim Bodnia, who is 56. He’s not as strong or fast as he once was, but he’s still very capable in a fight.

Witchers are far from the longest-lived denizens of the Continent. Mages have vastly increased life spans. Stregobor, one of the founders of the mage guild the Brotherhood of Sorcerers, was born in 786, well before the creation of the first witchers. Elves are also exceptionally long-lived.

The maximum lifespan of a witcher is unknown because they never actually die of old age. Their profession is so dangerous that most are eventually killed by the monsters they’ve sworn to eradicate. Witchers are rendered sterile by their mutations and the secret to the Trial of the Grasses was lost with the destruction of Kaer Morhen. Vesemir has been sadly watching his order shrink as fewer witchers return home to Kaer Morhen every winter.

Now you know how hard it is to guess a witcher’s age. No matter how they look, chances are they’re a lot older than you.