Badass Grandpa: Fan Works
- A Crown Of Stars: Daniel is a 452,388 years old Physical God. He wields many of the powers typically associated with physical gods -he is able to travel across time, space and dimensions, manipulate souls, warp reality...-, he commands a huge army -and is not afraid of kicking butts personally when it is required-, and as a bonus he has who-knows-how-many children and grandchildren.
- Thousand Shinji: In one of the last chapters Shinji finds an old bulldog and he is wary of it, realizing it was one of the creatures drawn to his girlfriend Asuka and therefore it had to be a fighter and a survivor (since that was the kind of animals that followed Asuka around). And if it was old and scarred, it had to have survived a lot of fights and dangers.
Shinji:As the saying went; always be wary of scarred old men, because the only thing you knew of them was that they were survivors.
- Tiberium Wars: Colonel (Retired) Nick Parker is an aging veteran of the First Tiberium War well into his seventies, spends much of his free time as a conservative pundit on the 24-hour news networks, and is twenty-percent cybernetics by this point. He also keeps a submachine gun in his car's glove compartment, can still land a headshot with a pistol at a hundred meters (left-handed), and once the Third Tiberium War breaks out starts hunting down and demolishing Avatars by his lonesome. "But that was why they called him 'Havoc.'" He's got a present for ya.
- He even volunteers to rejoin the war effort as an adviser to Commander Karrde when they ship out to Egypt.
- Aburame Katsu from The Middle Ground (A Naruto fanfiction) is so bad-ass he can make Jounin shake in their boots by drinking tea. His son-in-law Aburame Shibi considers him to be scarier than his maternal grandfather who was a prison torturer. In fact he's so bad-ass he can take down a minor in-clan rebellion by just making it generally felt he disapproves of it, without once even mentioning it. That's how bad-ass he is.
- In the Evangelion crossover HailToTheKing, you have Godzilla. Wordof God states that he is over 66 million years old, and is still the most powerful kaiju on either Earth. Anguirus, Mothra, and Rodan are also around the same age, and King Ghidorah is even older.
- The Firefly fic Forward has Shepherd Book further cement his badassery multiple times over the story, including having a scene where he silently knocks out several mercenaries while Mal keeps their leader distracted, and a particularly memorable moment where he saves River's life by facing off against an entire horde of Reavers singlehandedly, armed with nothing but a pistol and a sword.
- Fuhrer Grumman, of Fullmetal Alchemist, becomes this in the third part of the Elemental Chess Trilogy. He spends the first part being a Chessmaster who's pretending to be a Cloudcuckoolander and having great fun at everyone else's expense, and is absent for most of the second part, but in the third installment he survives an assassination attempt, utilizes a secret escape passage to fool everyone into thinking he didn't survive it, and then comes Back from the Dead to rescue his grandson-in-law from execution by firing squad.
- The Arbiter in The Last Spartan is in his golden years by the time he and Master Chief meet again, but even then, charges headlong into a warehouse full of mercenaries holding the Spartan prisoner with only Garrus Vakarian for assistance.
- My Little Mages: The Nightmare's Return: The Grand Master is an old man, but is still Nightmare Moon's most powerful minion — ultimately, only Pinkie is able to take him in a fight, and that's just because as his daughter, she knows how he fights.
- In the Uplifted series, Joachim Hoch becomes one in the first interlude. In his late 80's, having battled multiple bouts of cancer and survived World War II, he is still gearing up to lead the push to take back Rannoch from the Geth. He has decided that he can't even think of dying until he has set foot on, and preferably liberated the Quarian homeworld.
- Harry's martial arts instructor in Harry Potter and the Gift of Memories was over seventy and described as capable of routinely beating Harry "six ways to Sunday with one hand tied behind his back, hopping on one foot, while blindfolded."
- In A Scotsman In Egypt, King Edward of Scotland faces the Mongol Prince Subatai The Merciless in single combat. At the time of the duel, Subatai is 26 years old, and Edward is pushing 70. Place your bets on who wins, ladies and gentlemen. Hint: Don't choose Subatai.
Edward: "This? This is Genghis Khan reborn? This is the great Mongol warlord? This is the death of Scotland?"Edward: "THIS IS NOTHING BUT A PIECE OF SHIT!"
- Legendary Genesis's Headmaster Arcanine is remarkably strong and fast, and his senility makes him even more dangerous. Thinking his academy is under attack, he nearly ends up killing a couple of soon-to-be students.
- The Dusk Guard Saga: Captain Steel Song of the Dusk Guard is pushing 60, races the morning sun each day (and wins), and can kick manticore tail without much trouble.
- Roshi in Kitsune no Ken: Fist of the Fox is the oldest member of the Kyuushingai, but is perfectly capably of dishing out a beating to opponents.
- A Brief History of Equestria:
- Star Swirl the Bearded, who once took on all the assembled members of the Kingdom of Unicorns' Decadent Court during their attempted coup against the royal family and curbstomped them all by himself.
- Commander Hurricane was pretty much born a badass, so it should come as no surprise that he maintained this trait into his old age.
- Proving that the Badass trait is genetic, there's Hurricane's son Star Burst — well into his eighties, he personally led the defense during the Talonhoof Assault, at one point fighting Talonhoof himself, who was thirty years younger, and not only holding his own, but almost killing him twice.
- Talonhoof himself counts as well, considering that he's 50 at the time of the assault.
- Wandering Moon features Clover the Clever, Archmage of the past. She ends up taking on an ursa major (something that wasn't summoned earlier in a civil war between gods because a war between sun and moon hadn't quite crossed the Godzilla Threshhold). At the young age of 145. Her excuse is of course that there's an older badass or two that she's known.
- In the Fan Film Judge Minty, this is Deconstructed. Minty is still capable of dispatching numerous perps in his old days, but all his years of experience have taken a psychological toll in that he's become quite world-weary and prone to lapses in judgment.