Masked Invader: "I am surprised. It was quite easy to break into this room. Despite it being the office, or better, the personal room of the Captain-Commander of the Gotei 13. Isn’t security a bit too soft?"
Yamamoto: "There is no need to worry. I am here. There is no better security than this."
Arrancar version: Barragan Luisenbarn, owner of a frigging huge axe and with the power to age anything he touches or breathes on into nothingness. Barragan was "King of Hueco Mundo" before Aizen arrived.
Jack Rakan from Mahou Sensei Negima! is somewhere around 70 years old, but he is easily the strongest member of the cast after the centuries old Evangeline. He can fight an Ancient Dragon to a draw, blow up mountains by accident and survive getting hit by the magical equivalent of a tactical nuke. Plus thrashing a Nigh InvulnerableReality Warper without much trouble and willing himself back into existence after being erased.
Members of Rakan's race live much longer than humans. If memory serves right, Rakan would be in his mid-thirties in human years.
Joseph Joestar in JoJo's Bizarre Adventure Part 3. He may not get as many action scenes as he did in his youth so as to make place for the new protagonist, but he still displays his characteristic cunning (perhaps more than any other Jo Jo, he won his fights by outsmarting his opponents) by completely turning the tables on both the Empress and Mariah/Bast. Not in Part 4, though, where he is, indeed, too old and frail to still qualify as a Badass (though he doesn't lack courage at all, as proven in the Achtung Baby episode).
The Third Hokage is a bit of a subversion. While he does have a mastery of jutsu that Orochimaru can't begin to match, the ANBU members observing the fight realize that the Third has less chakra than he did in the past due to his old age. This is one major reason the Third had to resort to a Heroic Sacrifice to stop Orochimaru.
Jiraiya also counts, being around 50 at the time of his introduction, as a Kage-level ninja who spends his time writing porn and perving on young women.
There's also Jiraiya's former teammates Tsunade and Orochimaru, who are also in their 50s. The former is a badass grandma (just don't call her that unless your name is "Naruto Uzumaki"!) with super-strength and incredible medical ninjutsu skills that make her near-impossible to kill, even when she's cut in half at the waist. The latter may be a Mad ScientistEvil Overlord, but he's also the most talented ninja of the trio (and is possibly even more resistant to physical damage than Tsunade), being able to easily hold his own against high-level opponents even without the use of his arms.
Danzo. Although, at the age of 72, he normally appeared to be a frail old man, Danzo was actually an extremely powerful ninja. He was able to easily kill several would-be assassins and was able to fight on the same level as Sasuke.
Chiyo is a badass grandma. She's a 70-ish year old war veteran who's a specialist in poisons and a skilled puppeteer. With the help of Sakura, she managed to beat her grandson Sasori, perhaps the strongest ninja ever produced by the Hidden Sand Village, and his army of puppets. She used 10 puppets against his 100!
The Third Tsuchikage, Onoki of Both Scales, stands above them all. Despite being one of the oldest (mortal) characters in the series, he's still strong and fast enough to give modern-day shinobi an ass-kicking. In chapter 515, he's seen easily carrying an enormous island-sized turtle (one large enough to support its own ecosystem, complete with smaller but still very large animals on its back) with one hand thanks to his weight-decreasing jutsu.
He even stops Madara's Meteorite Attack, though he can't quite halt the second one.
The position of Kage has a very high mortality rate. Yet, he's the only active-duty ninja from Hiruzen's generation who has managed to live this long so far.
Hashirama Senju. Loving grandfather who spoiled his grand kids and One-Man Army who's widely considered the most powerful shinobi after the Sage of Six Paths.
Let's not forget Kakuzu, the Akatsuki member, S-rank criminal shinobi that is 91 years old, and yet he can make his body hard as rock, can move incredibly fast, can rip out his opponents' hearts, and has mastery over ALL of the jutsu elements! Being incredibly handsome is a plus.
From the original manga onwards, Master Roshi, the man who taught Goku his most powerful regularly used technique, was one of the very few people to beat Goku in a fight, and one of the most powerful humans alive at the beginning of the story, and at the end is still #4 or #5. Of his three latest students, two take the "strongest human alive" spot, and the other becomes "strongest anything anywhere", except perhaps for his own son.
Taken literally in the end of Dragon Ball Z and all of Dragon Ball GT. With Pan, Goku is a grandpa, and he's always been badass. Granted, he's not old, it's kinda made comical when he gets turned into a kid in DBGT. He's a Badass Grandpa who looks like he's 6.
In Tengen Toppa Gurren Lagann, we have Lordgenome. He looks like your average guy...or, uh, your average bodybuilder, not like he's over 1000 years old. However, in the final fight of the first story arc with Simon, after his mech gets wrecked, Lordgenome pops out of the cockpit and beats the crap out of Lagann bare handed. He eventually lost, and had his final monologue without a heart, lungs, etc. Later, he's brought back as a bio-computer, Futurama head-in-a-jar-style. In the final fight of the second story arc against the Anti-Spiral, Lordgenome first recreates his body and his mech from nothing in order to do battle. He holds back the Anti-Spiral's Infinity Big Bang Storm, an attack on par with the creation of the universe, eventually being disintegrated on a quantum level. However, he actually absorbs the attack and turns its power into pure Spiral Energy, to give to the good guys as his final Badass Grandpa act. It's a shame, he was content to sit on his throne for the rest of his immortal life, ruling Earth, having an infinite number of mistresses, but those silly protagonists forced his hand...
Lazengann, the personal mech of said Lordgenome, can be considered a Badass Grandpa Humongous Mecha. Despite being at least one-thousand years old, it is far from rusty and clunky, it kicks ass using kung-fu, and defeats the once-undefeated Gurren-Lagann with only a shredded hand to boot. The only reason it was defeated by Simon in Lagann was because of Simon's superior Spiral Power compared to Lordgenome's.
In The Prince of Tennis manga, Tezuka's grandfather Kunikazu is in his 70s, but still has incredibly sharp reflexes (is able to use chopsticks to catch a falling teapot) and is one of the most respected (if not feared) instructors in the Tokyo Police Academy.
Genji Kamogawa and Jinpachi Nekota. Both are in their 70s and retired, but still have impressive strength for their ages.
Kimura: (after seeing them exchange blows as a greeting)...THAT is how old men fight? Wow!
Their friend and rival Dankichi Hama also fits.
Ghost in the Shell: What's Aramaki's response to being captured and put at gunpoint? Call his captors dumbasses and order them around. And they listen. As does Section 9; an elite team of combat cyborgs, without serious question and with utmost respect, obeying a smallish older man.
Crossbone Gundam: Grey Stroke, an elderly Judau Ashta is possibly the best pilot in U.C. While everyone has their claim to fame, Grey Stroke can admit to living until 80 years old, piloting the Gump(a broken ZZ Gundam with a PEG LEG and barely any of the original parts) and defeating ZANSCARE EMPIRE MOBILE SUITS despite a tech difference of 60+ YEARS. To put in perspective how badass that is, imagine taking on F-22 Raptors with a makeshift-customized P-51 Mustang and winning.note The Gump may be an ancient machine with jury-rigged repairs, but it's still got the "bio-sensor" which has the mysterious ability to make a mobile suit faster, stronger and more durable when used by a powerful Newtype pilot whose emotions are sufficiently focused...and Judau is one of the three strongest Newtypes ever recorded. Also, there's also the part of him being one of the few, if not only major characters from the earlier U.C. series who actually survive to old age.
He shows up in Crossbone Gundam to lend Tobia Arronax a hand during one particularly strange mission (which coincidentally explains how the Gump got its aforementioned peg leg). Umon, one of the Crossbone Vanguard pilots meanwhile is mentioned as being a non-Newtype One Year War veteran who managed to scare the Nightmare of Solomon. While piloting a Ball.
More a case of a Badass Great Uncle than Grandpa but still...Thorkell the Tall. Pure Bad Ass, despite the goofy grin he's always sporting.
Askeladd's getting along in years as well, yet he is still stronger and harder than most men half his age.
Tenchi's grandfather Katsuhito in the Tenchi series, who is later revealed to be Ayeka's half-brother Yosho.
Some exposition may be needed, since there are like 5 different continuities. In the spoiler above is the case in the OVAs, and his feats include fighting off a brainwashed Ryoko who's under Kagato's control and fighting Kagato himself at the same time...and not even seeming to take the fight all that seriously.
In the Tenchi Universe series, he's still related to Jurai, but ran away to chill on Earth. As an old man, he...does fairly well...against the Big Bad Kagato who is his old friend and has a huge advantage due to a much younger body, and is introduced into the series by taking out a Galaxy Police Mecha with a wooden sword.
In Tenchi in Tokyo he's Guardian of the Earth, but he was getting Tenchi to take over.
In Magical Girl Pretty Sammy he never shows up, but in Magical Project S he makes a cameo as a sickly old man. Though he still talks like a badass though.
Hiko Seijiro from Rurouni Kenshin, Kenshin's teacher and master of the Hiten Mitsurugi-Ryu sword style, is an example of this trope. He is by far the most powerful swordsman in the series, capable of matching Kenshin, already established as an impossibly fast and powerful swordsman, in speed even when wearing a 30 kilogram cloak made of metal and possessing strength beyond any other character in the series by a ridiculous degree. In fact, during Kenshin's second training, Kenshin strikes at Hiko with his "entire body and soul" at one point (devoting so much attention that he fails to land properly and passes out), and only manages to graze one of Hiko's bracers.
Word of God says Hiko is so powerful that he could very easily take on virtually ANYONE in the series and completely curb stomp them.
Actually, Hiko is just in his 40s so he's still too young for it. (though very much in his way.) Nenji "Okina" Kashiwazaki, Misao's adoptive grandpa and the ex leader of the Oniwabashu, plays it straight...when he gets serious.
In Yu-Gi-Oh!, the Dark Magician becomes more powerful when aged a thousand years, becoming the Dark Sage.
Another example: If you read the Millennium World Manga, Yugi's Grandpa Sugoroku could be classified as this the combination of James Bond and Indy Jones has him investigating a a pyramid containing the Millennium Puzzle in a tuxedo!!!
"Dark King" Rayleigh certainly qualifies. He was the first mate of the former Pirate King, and after about 20 years is able to fight toe to toe with a Marine Admiral, one of the strongest fighters in the World Government (and in the case of this particular Admiral, capable of moving at the speed of light).
He swam across the Calm Belt. A strip of ocean filled with giant sea creatures that even the most hardened Marines & Pirates avoid. Why would he do this? Because His boat sank in the Grand Line, so he had to swim through part of the Grand Line in order to get to the Calm Belt. No problem for him. He had a message to deliver.
Vice Admiral Garp, the grandfather of the protagonist, who likes to attack people with a ball on chain the size of a boat, or throw/punch cannonballs at them. Which delivers the cannonballs at far greater velocity than any actual cannon could manage.
Edward "Whitebeard" Newgate, called "The Strongest Man in the World" has the power to create earthquakes and massive tidal waves, a particularly devastating ability considering that the entire One Piece world is one big ocean and a collection of islands and archipelagos. He controls a massive fleet of pirate ships, and is stated to have the power to destroy the world. Unlike many of the examples on this page, whose fighting abilities seem unaffected by aging in the slightest, the story makes it clear that age has already more than caught up with Whitebeard. He pulls off some of the most destructive and Bad Ass stunts seen in One Piece yet, and he does it all as a sluggish, half-dead shadow of the man he used to be.
And when he finally does die... well, to quote the book directly. "Even in death, even with half his face gone, he would never fall. He will forever be remembered as a monster for the way he destroyed his enemies that day. In this one battle alone he suffered 267 sword wounds, was struck by 152 bullets, and 46 cannon blasts. And yet neither that mighty body nor his pirate's pride suffered even one "coward's wound!" To put it in perspective: When his brain and heart stopped, his body didn't fall over. He had continued to fight for a good fifteen minutes after HALF OF HIS DAMN HEAD had been blown off by lava. Then he suffered a total of four hundred and nineteen sword and gunshot wounds, one of which is often an OHK device in manga, and the other of which is an OHK device in the real world. Additionally, 46 cannon blasts, which in the One Piece universe are inexplicably explosive, hit his actual body. And this was all in one battle. And over the hundreds of battles he'd fought in over 60 years, he had never been hit in the back because he had never turned away from a fight.
Brook, Strawhat Pirates's musician is an 88 year old skeleton who can play any instrument, runs on water and can make a sword attack so fast, that you realize you have been cut only when he re-sheathes his sword.
Master Yupa from Nausicaä of the Valley of the Wind is the ultimate Hayao Miyazaki Badass Grandpa. He wanders the world in peace and solemnity, looking for a solution to the Toxic Jungle, but also has a reputation across the entire world for being a legendary warrior. His finest moment may be stopping a sword at its point with his own forearm—and the force behind the sword in question is the title princess in an Unstoppable Rage.
From Berserk, we have Azan. He was once called the Bridge Knight for keeping one hundred knights from crossing a bridge, and while he's no longer in the prime of his life he's still able to match an injured, but still very mean protagonist, Guts in combat.
Hayato Furinji might be the baddassest grandpa of them all. His nickname translates to "The Man Without Enemies", because nobody in the entire world qualifies. He's only ever faced one opponent in his past that gave him trouble in a fight (it still ended in a draw). Unfortunately, it's implied that his opponent was Pencak Silat Master Silcardo Jenazad of YAMI. Another nickname (or perhaps a different translation of the same nickname) is "The Invincible Superman."
To get an idea at just what we're dealing with here, this is what Hayato considers holding back.
For further reference, he's currently operating at 0.0002 percent of his full power.
Watari. Not only is he able to put up with L (a fairly awesome feat by anyone's standards), he's also able to work round-the-clock with him and in the anime version, he shoots Higuchi from a helicopter at least 10 metres away.
Although he may not be quite on the level of Watari, there's also Light's father, Yagami Soichiro. Often cited as being the only truly righteous character in the Black and Grey Morality of the series, he pulls off various feats of badassery in the name of his idea of justice.
Just to give you an idea, he rammed a van into a TV station in order to shut down the pro-Kira broadcast. And in the manga and anime, this was after suffering a heart attack.
In 20th Century Boys, a couple time skips causes the original main cast to become this. "When a man is singing, you DON'T SHOOT HIM!"
Yagyu Retsudo from Lone Wolf and Cub. Despite his old age he virtually controls the nation and is equal in combat with the main character (who is awlays portayed as the most skilled swordman).
Shiryu's master Dohko from Saint Seiya. He is a subversion, though, since thanks to his powers, his old appearance is just an illusion and he hasn't really aged at all in 200 years.
Balgus from Vision of Escaflowne definitely counts for chopping off the arm of a mecha with a giant sword, on foot. The only reason he lost was because he was fighting giant robots. On foot.While protecting someone. He would've been fine if he'd been alone.
Bookman from D.Gray-Man. Just try to call him "Old Panda" and you'll see.
Tokaki and his wife Subaru from Fushigi Yuugi are Badass Grandparents, fighting demons and the Seiryuu Seishi Miboshi at over 100. Justified as both of them are Byakko Seishi. Tatara, their fellow Seishi, is a subversion of this trope, seeing as Subaru cast a spell on him to make him look, feel and fight like he's younger.
While not actually related to anyone, and a Dirty Old Man to the core, Happosai of Ranma ˝ is also a legitimately dangerous old man who, when he puts his mind to it, can be the most powerful Old Master in the series. Though one of two Miniature Senior Citizens, he has once stopped a bomb the size of a small house with just his finger, sent a giant yeti-ox-crane-eel mishmash rocketing skyward with only his pipe, knocked said abomination against nature out with a single one of his homemade bombs, can use his Battle Aura with such proficiency he can grow into a kaiju-sized giant version of himself, and can defeat any combination of the teenaged cast with no difficulties whatsoever.
Toriko has THREE Badass Grandparents. There's "Knocking Master" Jirou who can ressurrect the recently deceased through acupuncture among other thingsd, his cook, Setsuna the Gourmet Living National Treasure who can easily break the Big Bad's Dragon's weaponry through sheer force of will, and finally there's Ichiryuu, president of IGO who recently either stopped or tanked every attack from Toriko and then casually one-shotted him.
Professor Oak is still a pretty good fighter, even though he actually is a grandfather in Pokémon Special. Agatha is the same age, and is a member of the Elite Four. Wattson and Pryce also probably count. Bertha will probably be added to the list once she makes an appearance.
Xerxes Break of Pandora Hearts qualifies as well. While his body doesn't show visible sign of aging, he couldn't possibly be any younger than seventy, with eighties or nineties being more likely, and he is still aging on the inside, often making reference to how surprised he is he hasn't died yet. While Break's main power is technically the Mad Hatter, he's a pretty good badass in his own right- even moreso in the anime, where in episode 24 he takes on dozens if not hundreds of giant supernatural abominations with his sword while his comrades are struggling to fight them with Chains. Before finally just calling out the Hatter to cleanse the entire city of a few thousand rogue chains in seconds.
For a villain example, we present you Hades of Grimoire Heart, the former master of Fairy Tail. He seems to be at least a few decades older than Makarov (and Makarov is 88!), but still kicks Makarov's ass without any seemingly problem.
Nurarihyon from Nurarihyon No Mago, the eponymous character's grandfather. Though the years have not been kind on him, as he is now far from what he was back in his prime, he still manages to curb stomp Rikuo in a fight.
Sir Archer from ''Lupin III" Pursuit Of Harimao's Treasure, in his youth he was a former soldier and a secret agent for the British Secret Service, in his 80's he can defeat several armed soldiers in combat.