If there's one thing Thanos is famous for, it's blinking a whole lot of people out of existence with a simple snap of his fingers. First appearing in 1973, Thanos has long been one of the most dangerous characters in the Marvel universe. Even beyond the god-like powers bestowed by the Infinity Gauntlet, Thanos is still hugely powerful. Outright one of the most physically powerful beings in the mortal universe, he's gone toe-to-toe with entire teams of Avengers and come out ahead. He's beaten down everyone from Captain America to Galactus himself. Even beyond his extreme physical strength, he's got energy projection on par with Captain Marvel, mind powers that allow him to manipulate and corrupt without saying a word, and he has access to highly advanced technology and even magic.
But this list isn't about how powerful Thanos is (directly, anyway). This list is about all the people Thanos has whomped in his 45 years of existence. We'll mostly avoid all the characters that got snapped out of existence with the Infinity Gauntlet, and stick to characters he's snapped in half with his un-Gauntlet'ed fists. We will be dipping into a few alternate timelines and technicalities, where he manages to take out a huge number of people through trickery or deceit. After all, Thanos' vast intelligence is just as much a weapon for him as his massive strength or immense energy powers. There will be a few defeats from Infinity Gauntlet itself, but none that came as part of the fateful snap.
Hulk is the strongest one there is. Thanos, while not necessarily labeled as the strongest, is pretty up there. When the two clash, the very foundations of the Earth can quake. In Infinity War, Thanos trounced Hulk pretty easily, without even using the Power Gem. This beat Hulk back into Banner, refusing to aid the Avengers in the final battle.
In the comics, things went about the same. In the alternate continuity of Donny Cates' Thanos Wins, Thanos defeats Hulk so hard that Hulk is reduced to little more than an animal. He becomes a pet for Thanos' amusement, executing what few enemies remain that Thanos doesn't want to deal with himself.
19 BLACK BOLT
Black Bolt and the Inhumans often get ignored in favor of the X-Men, but in reality, Blackagar Boltagon is one of the most powerful Earth-based heroes. In addition to his standard flying brick powers, his voice is an immensely powerful weapon, where even the barest whisper can destroy a city.
His voice did him little good against Thanos during the events of Jonathan Hickman's Infinity. Severely weakened by detonating the Terrigen Bomb in an attempt to stop Thanos, his voice does little against the Mad Titan. Even a shout straight to his face barely even fazes Thanos, who pummels the Silent King into unconsciousness.
18 WAR MACHINE
In the prelude to Brian Michael Bendis' Civil War II, Thanos, inexplicably armed with a gun, attacks a secret facility on Earth in order to steal a Cosmic Cube. Carol Danvers, warned ahead of time by a new Inhuman, assembles a team to fight off Thanos before he has a chance to do something terrible.
On that team is James Rhodes, the War Machine. Proving to be woefully underpowered to fight the Mad Titan, Rhodey first blows up She-Hulk with a supposed anti-Thanos missile, before getting his middle bits replaced with Thanos' fist. Thanos is defeated shortly thereafter, but Rhodey's death would lead to the conflict between Tony Stark and Carol in the main event.
Annihilus is right up there with Thanos as one of the foremost cosmic threats to the Marvel Universe. The leader of the Annihilation Wave, Annihilus' only goal is to expand the Negative Zone and subsume the positive matter universe. Even without the endless hordes of the Annihilation Wave behind him, he is still a formidable physical threat.
When he faced Thanos, he had managed to copy the Hulk's transformation, growing into a giant. This led to Thanos' defeat in their first battle, and Annihilus nearly destroyed the universe. His plans were reset by Adam Warlock, and Thanos squished the Lord of the Negative Zone after Warlock reduces him to a tiny bug.
Phyla-Vell is the Captain Marvel everyone forgets, and the one everyone who remembers her wants back. First appearing during Genis-Vell's time, she would take over the mantle with Genis' death. She would go on to be a part of the rebooted cosmic storyline started in Annihilation and continued in Annihilation Conquest.
She joined the Guardians of the Galaxy, and fought against various foes in her time with them. Her final conflict would be against the Magus, a dark reflection of Adam Warlock. She and Magus would trade defeats, until ultimately she came before what she thought was Magus' cocoon. As she approached, it hatched, revealing a resurrected Thanos, who immediately slew her.
This one sure seems like a bit of a gimme, since Deadpool is just really good at regenerating and Thanos is one of the most powerful people in the Marvel universe. But still, Deadpool got whomped pretty hard. A lot of Thanos' motivation comes down to his deep and abiding love for the cosmic abstract Death. Deadpool also loves Death.
Thanos, not one to dignify rivals, first went to beat the ever-loving heck out of Deadpool. After reducing him to a bloody paste, Thanos then cursed Deadpool to never die, an already difficult task given the Merc With a Mouth's healing factor.
14 ADAM WARLOCK
Before Jim Starlin created Thanos, he created Adam Warlock. Warlock would become one of the centerpieces of Cosmic Marvel, and one of Thanos' longest-lasting foes. He was the first to hold the Soul Gem, and used it multiple times to save other heroes' souls from death. Naturally, this eventually brought him into conflict with Thanos.
Thanos, having gathered the Infinity Gems for the first time, plans to snuff out all the stars in the universe. Enlisting the aid of the Avengers, Warlock and Captain Marvel take the fight to Thanos to thwart his plans. Warlock confronts Thanos directly, and is struck down almost immediately.
13 SILVER SURFER
One of Galactus' most powerful heralds, the Silver Surfer is a cornerstone of the Cosmic Marvel universe. In the pages of his solo series, Thanos returned from his death at the hands of Adam Warlock. The Surfer tried to stop the Mad Titan, but his powers were ineffectual, and Thanos fooled him into believing that he had come out victorious.
Later, in an alternate future, an aging Thanos would confront an older Silver Surfer. This version of the Surfer had lost his silvery sheen, but had gained control of both the Annihilation Wave and Mjolnir. With the help of his younger self, Thanos managed to deliver the Surfer to his ultimate end.
12 DRAX THE DESTROYER
Thanos is one of the most powerful and dangerous beings in the Marvel universe. Naturally, this means some people are going to oppose him. After Thanos ends human Arthur Douglas' family, Thanos' father Mentor chooses Douglas to be his weapon against Thanos. Transformed into Drax the Destroyer, his sole purpose becomes ending Thanos.
He finally succeeds in Annihilation, ripping Thanos' heart from his chest. However, he is forced to team up with a resurrected Thanos against the threat of the Cancerverse. Although he manages to keep things under control for a while, he eventually loses it and goes after Thanos again. It is revealed that Death has rejected Thanos, and upon his immediate return, he dispatches Drax easily.
Here's one of those Infinity Gauntlet defeats Thanos doesn't use the Gauntlet for. After the fateful snap wipes out half the life in the universe, the surviving Avengers gather up what heroes they can and go to confront Thanos directly. While Thanos wipes out most of the heroes with the power of the Infinity Gauntlet, Vision's demise is a little more brutal.
Managing to catch Thanos unaware, Vision phases through the Mad Titan's body. Although this throws off Thanos for a moment, he quickly recovers. In an image reminiscent of our movie-only crowd, Thanos reaches into Vision's chest and comes out with a fistful of sparking wires.
10 CAPTAIN AMERICA
Although Vision got one of the most brutal defeats in Infinity Gauntlet, Captain America's confrontation with Thanos is by far one of the most iconic images in the comic. As the rest of the Avengers and other Earth heroes lie defeated before Thanos, Captain America strides up to confront the Mad Titan alone.
He tells Thanos that as long as one man stands against him, he'll never be able to claim victory. He then attacks Thanos, even managing to stand up to a few blows before his shield is shattered. Thanos then casually defeats the Captain with a backhanded slap.
9 MONICA RAMBEAU
Another former Captain Marvel, Monica Rambeau is just about the most powerful Earth-based superhero. Her powers allow her to turn into any form of electromagnetic radiation, including light. They have progressed to the point where she has transformed into a being of hard light, rather than a flesh-and-blood human.
As a member of the Ultimates, she took part in a battle against Thanos after he escaped from capture. Monica's tried and true strategy is transforming into light, flying into an enemy's eye, and directly attacking their brain. When she attempted this with Thanos, his mental presence was so strong that it forced her out of his skull and knocked her unconscious.
8 AMERICA CHAVEZ
America Chavez is a hot-blooded teenager with attitude. In addition to her signature star-shaped interdimensional portals, she's a high-level flying brick. Unfortunately, this great power leads into one of her greatest failings: her overconfidence in her own abilities. Due to never really facing failure or a challenge, America developed an attitude that could generously be called "grating."
As part of the Ultimates, she also took part in the battle against Thanos. Unlike previous battles she's participated in, she got absolutely walloped. Thanos wiped the floor with her, casually brushing her off not once but twice before being defeated by the older and wiser members of the team.
7 THE CHAMPION
In Thanos' fateful quest to gather the Infinity Gems, he came into conflict with the Elders of the Universe. A group of powerful, immortal beings, the Elders have caused trouble for Earth heroes time and time again, particularly the Grandmaster and the Collector. In the interim between Thanos' first demise and his return, they had each acquired an Infinity Gem.
The first he confronts, the Champion, claims to be the greatest warrior in the universe. Indeed, he manages to match Thanos in single combat with the might of the Power Gem. Thanos, however, tricks the Champion into destroying the planet they are battling on, leaving the Champion stranded in space.
6 THE GRANDMASTER
The Grandmaster is a long-time foe of the Avengers, often kidnapping various groups of heroes to participate in some form of blood sport or another. As an Elder of the Universe, he came into possession of an Infinity Gem while Thanos was busy being a statue. When Thanos returned from Lady Death's realm, he began his quest to gather the Infinity Gems.
The Grandmaster ended up being the last holder on Thanos' list. Because of his obsession with games, the Grandmaster agreed to give Thanos the Mind Gem if he could defeat him in a game. The Grandmaster quickly cheated, although Thanos revealed that he had sent a robotic duplicate into the game. The real Thanos proceeded to destroy the gaming equipment, leading to the Grandmaster's demise.
5 THE ENTIRE CANCERVERSE
At the end of Dan Abnett and Andy Lanning's cosmic Marvel saga, the universe was invaded by another universe. This other universe, called the Cancerverse, had sacrificed their Lady Death. This caused life to expand without limit or control, subsuming the universe in a Lovecraftian horror show.
In order to defeat this threat, the Guardians of the Galaxy sought out a reborn Thanos to help them against the threat. Eventually, it came down to Thanos and the Cancerverse version of Mar-Vell, the originator of the curse that took over the Cancerverse. As Mar-Vell prepared to end Thanos, 616's Lady Death arrived to claim him. This returned Death to the Cancerverse, wiping out the corrupted heroes.
Galactus was the very first cosmic level threat to be introduced into the Marvel Universe. First seen in Fantastic Four #48 in 1966, Galactus opened a galaxy of trouble for Marvel heroes. He would continue on not as an outright villain, but more as a force of nature who occasionally needed to be opposed by heroes.
In the alternate future of Thanos Wins, Galactus is one of the last remaining cosmic beings opposed to Thanos' omnicidal rampage. After getting beaten once, he attacks Thanos once again, this time with the help of a cosmically powered Ghost Rider and a really big gun. This goes very poorly and Thanos blows Galactus' head off with eye beams.
3 LADY DEATH
In the Earth X continuity, things get very weird very fast. After the events of Earth X, most of the heroes are hanging around in heaven for Universe X and Paradise X. In Universe X, Lady Death seeks to destabilize the universe so the Celestials can infest and breed more planets within it.
Using Thanos to mount her attack on the Realm of the Dead, she battles against a multitude of deceased heroes led by Mar-Vell and Captain America. Mar-Vell reveal's Death's manipulations to Thanos. The heartbroken Thanos confronts Lady Death, only to have all his fears confirmed. He then uses the Ultimate Nullifier to destroy the cosmic abstract.
Thanos has trashed a whole lot of people in his time as a marauding warlord out to wipe out half the life in the galaxy. Thanks to the power of the Time Gem, he finally got the chance to take on his true greatest enemy: himself. In Thanos Wins, an aging Thanos is one of the last living things in the universe.
He brings the present-day Thanos into the future, ostensibly to help him defeat his final foe, a fallen Silver Surfer. In reality, Old Thanos wants Young Thanos to finish him off so he can finally be with Lady Death. Young Thanos at first agrees, before taking a different path. Not wanting to become like the tired and broken old man before him he returns to the present and vows to never become the Old Thanos he saw in the future.
No, we're not talking about his snap in Infinity Gauntlet. After all, that was only half of everyone. No, we return to Thanos Wins for one final entry. As Thanos grows older, he doesn't get slower or weaker, like mortal heroes. He only gets stronger and stronger. Eventually, he goes on a rampage across the universe, slaughtering everything and everyone in his path.
He starts with all of Earth, and only goes bigger from there. Gods, Galactus, and other cosmic abstracts fall before him. His last foe is a fallen Silver Surfer, armed with Mjolnir. Even then, at the end of everything, he still needs his younger self to finish the job so he can finally be with Lady Death.