He is a rotting carcass writhing invisibly with power from the Dark Age of Technology.
They may be very old, or crippled, or ill, or some combination of the three. A slight breeze looks like it could kill them. Either way, they do not cut an imposing figure in person. They may be incredibly competent in internal politics, but they don't do anything except be Orcus on His Throne because, well... they looks like they can barely get off it. Sure, they might have been The Conqueror in their younger days, but those days are long gone by. Bonus points if there appears to be some sort of cult worshiping them or the reader is repeatedly told In-Universe accounts of how amazing or impressive they are.
The key to being this trope is that despite how decrepit or powerless they may be physically, the state or authority they are at least nominally the head of is decidedly not, and defying it is no laughing matter in the setting. Also, if the setting includes magic or some equivalent to it, this guy could very well be extremely talented in its use and legitimately capable of defending himself with it, though anyone who can get around said magic will probably have no problem with assassinating him.
- In Aldnoah.Zero, the Vers Empire is led by Emperor Rayregalia Vers Rayvers. Publicly, he appears to be a strong and confident man. In reality, the strong image he projects is a literal holographic illusion, and the real Rayregalia is a dying, senile bedridden invalid who is being led around the nose by Count Saazbaum. In the second half of the show, his physical condition further deteriorates to needing a respirator, and his mental state collapses even further to the point that his mind regresses decades back to the time when his son was still alive, alternating between delusional and lucid. It is strongly implied he dies shortly before the end of the series.
- Whitebeard, one of the Four Emperors from One Piece zigzags this to the extreme. On one side, he's introduced being hooked on life support despite being captain of one of the strongest crew in the world, with claims over large territories in the New World. During the Paramount War arc, he insisted on taking the life support devices out so his enemies won't pity or mock him for it, and even his subordinates note that this man is way past his prime, terminally ill and practically on death's door. On the other hand, he's still a massive, towering bulk of muscle, and he will show you just exactly why he's earned the title of World's Strongest Man.
- In I Am Skantarios, the Pope — by dint of his authority over Western Europe — is portrayed as a serious threat to the Byzantine Empire, culminating in a Duel to the Death between the titular Skantarios and the Pope. However, the Pope is eighty and has never used a sword or ridden a horse before in his life, so the duel is... anticlimactic.
- Star Wars: Emperor Sheev Palpatine founded and leads the mighty Galactic Empire — yet in The Empire Strikes Back, he is revealed to be an old man in a simple black robe, and in Return of the Jedi he is shown as being much smaller than his apprentice, Darth Vader. This trope gets zig-zagged a bit, as he is a genuinely powerful Sith Lord who is incredibly talented in the ways of the Force... but he's also a very old man decades past his prime, meaning that while he can kill easily with the Force, he's pretty helpless against anyone or anything that can get past that. Darth Vader defeats him by simply bear-hugging Palpatine and hurling him over a nearby railing to his death, and Palpatine can do nothing about it but scream and wildly fire off Force Lightning.
- In Fatherland, Hitler's Nazi Germany has conquered Europe, and he's still in charge twenty years later. While he never shows up in the book, at the end of the movie he turns up for a diplomatic meeting with the U.S. President in Berlin, showing him to be a feeble 75-year old man.
- Malkariss from the Redwall book Mattimeo founded an immense subterranean civilization on slavery and speaks from an imposing statue — but is elderly, frail, and nearly blind, and depends on his servants to run his empire according to his orders.
- The Emperor of the Agatean Empire in the Discworld book Interesting Times. He is bedridden, speaking is difficult for him, and there are already internal power struggles... yet he still orders executions left and right, and his empire has nearly a million men under arms.
- Cleon II and the Mule from Foundation. The former is the last strong Emperor yet bedridden due an unknown and painful disease, the latter is a mutant with enough power to build a huge empire, a frail build, and enough health problems to die before he's fifty.
- God in His Dark Materials is so old and frail that he is literally killed by a slight breeze.
- In The Traitor Baru Cormorant, the Emperor at the head of the Imperial Republic of Falcrest is actually a lobotomized puppet, and the Parliament has no real power either. Instead, all real power is in the hands of a cabal of "advisers" operating behind the scenes.
- Played With in Mistborn with the Lord Ruler. The nature of his powers make being Orcus on His Throne a necessity, especially because he needs to spend some periods of time as a shriveled old man in order to spend other times as a healthy, young man, despite being centuries old. However, when he takes an active role in the first book, he's a nearly invincible Physical God rather than the nominal ruler that would be expected from his absence from public life.
- In The Man in the High Castle, Adolf Hitler has conquered half the world, The Holocaust has gone through, and the only other country is his wartime ally Japan... yet he is in his seventies at the start of the series, with failing health, and it is admitted that he will probably die soon. The original novel takes it even further; Hitler no longer rules the Nazi empire he founded, instead rotting away in a lunatic asylum as he dies of old age, all while the rest of the Nazi leadership tries desperately to pretend that they didn't build a world off the ideas of a man even they now know to be insane.
- Babylon 5: While Centauri Republic is an empire in decline, they still rank among the five most powerful races in known space. The emperor, however, is a very old man who is gravely ill. At least at first; when he makes a visit to Babylon 5, his health takes a sudden turn for the worst and he dies shortly thereafter. His replacement is a much younger man, but is really not right in the head.
- In The Borgias, the King of Naples was a highly feared man who was known for his cruelty. By the time he first shows up on-screen, he's old, frail, and possibly senile, making him an easy target for torment by his own son Alfonso.
- The God-Emperor of Mankind from Warhammer 40,000 is the nominal leader of the Imperium of Man, which controls the majority of the setting, but has spent the past ten millennia on life support while his body has decayed to a skeleton; although he has immense psychic power, most of it is used on maintaining a beacon to use for humanity's FTL Travel. Outside of this functionnote , the Emperor is effectively a figurehead, while the day-to-day administration is left to the High Lords of Terra, and each system is controlled by its own local planetary governor. Very much averted in the backstory, where he was — among many other things — a brilliant example of an Emperor Scientist.
- When EVE Online launched, the current God-Emperor of the Amarr Empire (the game's largest NPC Empire) was Heideran VII, who was well over 700 years old and confined to his life support throne.
- In most of the games based on The Simpsons, specially the Konami's Beat 'em Up of The '90s and The Simpsons Game, the Big Bad is usually Montgomery Burns, a frail, ridiculously old man who can be easily defeated — even by Maggie.
- Final Fantasy VI has the Gestahlian Empire, which covers the known world and is run by Gestahl, a 60-year old geezer.
- Final Fantasy XV subverts this; the Empire of Nifleheim is nominally governed by the Emperor Iedolas Aldercapt, but the de-facto ruler and actual Big Bad is his chancellor Ardyn Izuna, who looks much younger due to being immortal.
- Final Fantasy XIV subverts this as well. The Emperor and founder of the Garlean Empire, Solus zos Galvus, is never even seen outside of official developers' artwork, and he's an old man in his eighties by the time the game starts. Before the first expansion, he dies offscreen due to illness and old age and the ensuing Succession Crisis happens entirely independently of the player or their allies. His grandson, Varis, then takes over. Two expansions later, it's revealed that Solus was actually one of the immortal Ascian sorcerers, had several clone bodies, and is in fact very much still alive - he only took a short nap in the Interdimensional Rift after the death of his mortal body and later happily comes back into the picture by messing with his grandson and monologuing about how the Garlean Empire was simply a tool of the Ascians. Soon after, we learn his Ascian name - Emet Selch - and he steps into the Big Bad role for the Shadowbringers expansion, and he is anything but this trope.
- The Empire of Adrestia in Fire Emblem: Three Houses is led by Emperor Ionius IX, the father of Edelgard von Hresvelg. Ionius is a man in very ill health and in reality has barely any political power, having been rendered powerless in a silent coup by an alliance of corrupt noble families and by Those Who Slither In The Dark. He is so powerless, that he was unable to prevent his 11 children from being kidnapped, imprisoned, and experimented on to become double Crest implantees, with 10 of those children eventually being tortured to death. The horrible state of his health is the major factor that allows Edelgard to return to the capital and ask him to step down so she can ascend the throne, averting this trope (well, for as much as she can, since her health also ended up rather damaged by the aforementioned experiments — of which she was the Sole Survivor).
- The Owl House: Emperor Belos, ruler of the Boiling Isles and overseer of the coven system, is hinted to be this. He rarely makes public appearances anymore, operating through intermediaries without leaving his palace, and when he finally see him towards the end of season one, he's visibly ill and has to feed on the magic bile from a palisman to function normally. Despite all this, he's still the most feared man in the Boiling Isles, and with good reason.
- Timur the Lame was crippled for most of his life, but managed to carve out an mighty empire that only grew more powerful as he became older. By his late sixties, he could barely hold a sword or mount a horse alone, but succeeded in crushing the Georgians, Armenians, Persians, Egyptians, Indians and the Knights of Rhodes, and humiliated the rising Ottoman Empire by taking its sultan prisoner alongside his entire harem with him.
- The British Empire during the second Boer War, with Queen Victoria in seclusion and on her deathbed for most of the war.
- In the United States — one of the most powerful nations on Earth and arguably the center of a cultural sphere of power that extends worldwide — the President must be at least 35 years old. While that's nowhere near this trope, most Presidents are, in practice, nowhere near that age; POTUSes in their 40's are considered almost too young. The typical President of the United States is in his late 50's to early 70's; Ronald Reagan was nearly 70 when he was elected (at that time the oldest elected president, until surpassed by Donald Trump who was exactly 70 by his election in 2016) and a few weeks shy of his 78th birthday when he left office. A more specific example is during WWII, the president of the US was F.D.R. who was in his '60s and was in a wheelchair due to Polio.
- The USSR — the other official superpower during the Cold War — had not one, but three Secretaries-General of frail health from the late 1970s to mid-1980s: Leonid Brezhnev, Yuri Andropov and Konstantin Chernenko. The first half of 1980s was jokingly (in a dark way) called 'the Five Years of Fabulous Funerals' or 'Bier Racing'. Then a younger, more energetic person took the position and started to reform the country... we all know how it ended.