"Harry: So if I go back in time and kill my grandfather, what happens?
Vadderung: He beats you senseless, I suspect."
― The Dresden Files
"Even his experience doesn't compare to mine."
― Chiyo (Naruto)
"You're a million years too young to challenge me."
― Tsuru (One Piece)
"Mightily Oats: You're really going to let a little old woman go out and fight monsters!?
Mob: Why should we care what happens to a bunch of monsters? "
― Terry Pratchett, Carpe Jugulum
"Dead almost 20 years, you're still taking me to school..."
― Tony Stark (Iron Man 2)
The ability to be in top condition while at an old age. Opposite to Child Prodigy.
The user has great status both mentally and physically despite their old age either from years of training or off the fly making their opponents often underestimate them as well and they make it appear as if time has had no effect on their physical condition making them a force to be reckoned with. Some users have great intellect and are capable of being master strategists as well.
Maz Koshia (The Legend of Zelda: Breath of the Wild)
Shun Di (Virtua Fighter)
Ana Amari (Overwatch)
Albus Dumbledore (Harry Potter)
Minerva McGonagall (Harry Potter)
Lord Voldemort (Harry Potter)
Montolio Debrouchee/Mooshie (Forgotten Realms)
John Wakefield (Harper's Island)
Iroh (Avatar:The Last Airbender) the Dragon of the West.
The White Lotus Order (Avatar:The Last Airbender)
The Avatars (Avatar:The Last Airbender/Legend of Korra) of the past.
Despite being 66, Judge Dredd (2000 AD) is a legendary lawman and Judge in both in Mega City and the Waste.
Max Tennyson (Ben 10) was a semi-retired legendary Magister rank Plumber and is the mentor of Ben, Gwen, Kevin, and the Plumbers' Helpers. Max is widely considered the greatest Plumber in the Milky Way.
Hex (Ben 10), a master magician at age 62.
Despite being around 60 years old, Slade Wilson (DC Comics) is considered one of the world's greatest mercenary of all time due to a failed medical experiment he had volunteered for when he joined the military.
Superman (DC Comics)
The Batman of Earth-31 (DC Comics)
Splinter (Teenage Mutant Ninja Turtles)
Master Yoda (Star Wars) was considered to be one of the most skilled users of the Force in the universe.
Aged 120, Isaac Netero (Hunter × Hunter) can fight toe-to-toe with the strongest Chimera Ant Meruem.
Zeno Zoldyck (Hunter × Hunter) attempts to assassinate the Phantom Troupe's leader, Chrollo.
Despite his advanced age, Genryūsai Shigekuni Yamamoto (Bleach) was considered to be the strongest Soul Reaper in existence for the last millennium.
Ichibē Hyōsube (Bleach) is one of the oldest Soul Reapers, possibly older than even Yamamoto, and is also one of the strongest beings in existence.
Yhwach (Bleach) is the first and most powerful Quincy to have ever existed.
Though not as powerful as he was in his prime, even in old age, King Piccolo (Dragon Ball) wields frightening power, easily outmatching Goku and beating him to the point where his heart temporarily stopped.
Despite his advanced age, Master Muten Roshi (Dragon Ball series) is a very skilled and experienced warrior, enought to earn the respect of the God of Destruction.
King Bradley/Wrath (Fullmetal Alchemist) is a very strong swordsman despite his body often feels the effects of old age.
Walter C. Dornez (Hellsing)
Tsunade (Naruto) appears to be a young woman, but she is already in her 50s, using her superhuman strength and a transformation technique to mask her physical appearance.
Despite being 91-years-old, Kakuzu (Naruto Shippuden) is one of the most powerful and dangerous member of the Akatsuki.
Despite his old age, Whitebeard (One Piece) was still considered one of the most powerful men in the world before his death.
At the age of 68, Charlotte "Big Mom" Linlin (One Piece) is one of the four most powerful pirates in the world.
Brook (One Piece) is a veteran 90 years old pirate and a master swordsman.
While in his late 50s, Kizaru (One Piece) is an extremely powerful Marine Admiral.
Despite being a blind elderly man, Fujitora (One Piece) is an extremely powerful Marine Admiral.
Despite being in his 70, Monkey D. Garp (One Piece) is still considered one of the strongest marines alive.
Kureha (One Piece) is a genius doctor who has lived up to the age of 141.
While over 70 years old, Silvers Rayleigh (One Piece) is still one of the strongest people in the world.
Despite being nearly 80 years old, Sengoku (One Piece) was a Fleet Admiral of the Marines and one of, if not the strongest amongst their ranks, able to even battle the Blackbeard Pirates by himself.
All Minks (One Piece) are natural born fighter who retain their physical prowess even in old age.
Though elderly, Nekomamushi and Inuarashi (One Piece) are the strongest of the Mink tribe.
Despite being elderly, Hayato Fūrinji (History's Strongest Disciple Kenichi) is a powerful martial artist in prime condition.
Cologne (Ranma ½) looks like a deformed she-gnome, measures her age in centuries rather then years, and can still beat down any two of the teenage martial artists at the same time.
Happosai (Ranma ½) one of the two by-far most skilled characters in the series, and likely easily the most powerful chi-user.
Though not as powerful as she was in her prime, Genkai (Yu Yu Hakusho) remains a formidable fighter.
Despite his old age, Bang (One-Punch Man) is ranked 3 among the strongest of the Hero Association and founder of his own brand of martial arts.