“Enter through the narrow gate, because the gate is wide and the way is spacious that leads to destruction, and there are many who enter through it. But the gate is narrow and the way is difficult that leads to life, and there are few who find it."
In works where God Is Evil (or at least impossibly strict), the road to Hell is sometimes defined to be so wide that people with basically slight or even no sin at all will end up there anyway. This is typically done to make sure that people will stick to a very straight and very narrow path, or at least try to. Some authors have taken this ease of entry into Hell Up to Eleven, making it not just easier, but almost automatically assured for everyone. In universes like these, All Sins Are Equal, which tends to lead into It Gets Easier, as once one is trivially doomed to Hell, doing some "worse" things will not change anything.
In other words...
In Hell Girl, all that's needed to go to Hell is for someone to hate you enough to be willing to use the Hell Correspondence and make a deal with the title character to send you there — or to make the deal yourself, as once you've sent someone to Hell you will also go there when you die. People have been sent to Hell for spilling coffee on someone on that show.
Literally going to Hell seems to be pretty rare in Bleach, but since your other options for afterlives are a desert where monsters hunt you until you become one of them and a depressing slum where you will live in poverty and Medieval Stasis while ruled over by unquestionable overlords (unless said overlords recruit you, in which case you will serve as a soldier until the aforementioned monsters manage to brutally kill you), going figuratively to Hell (that is, being sent to an awful and inescapable afterlife) is, to the best of our knowledge, a complete certainty.
To be fair, only part of Soul Society is poor slums. Plenty of the Rukongai is nice and peaceful, and being a Shinigami seems to guarantee you a nice life in the Seiretei (unless you get put under Captain Mayuri's command, or are too weak to avoid being killed by the Hollows). Additionally, Soul Society serves more as a sort of hostel for the souls of the dead until they are eventually reincarnated anyway, rather than necessarily being a final destination.
In Berserk, the two afterlives that we know of are either to become a restless spirit (likely because of Unfinished Business) or get sent to the Abyss (if you became an Apostle, are branded as a sacrifice, died with hatred in your heart, or any of a great number of things). While the Abyss is stated to be what most people think of as heaven or hell, any human who goes there has their ego dissolved, so most people would consider it to be Hell. Seemingly the best afterlife in this Crapsack World is no afterlife at all, which might not even be possible.
Chick Tracts simultaneously play this straight and invert it: everyone is going to hell for the slightest, and least objectionable, of sins. However all you have to do is accept Christianity as he defines it and you'll spend eternity in heaven, no matter how horrible your previous actions. Some older tracts which pushed this "logic" far past the breaking point note For instance a vicious multiple murderer who accepts Jesus the night prior to his hanging being saved, while the moral sheriff who stopped his killing spree getting damned forever were pulled out of circulation by Chick himself when he realized that the massive Moral Dissonance was too much for virtually anyone not as extreme in their beliefs.
In both the DC and Marvel 'verses there have been examples of people getting sent to Hell with magic, rather than through any fault of their own. Granted, in most such cases they were able to get out later.
The Bible, as quoted above. It repeatedly states that all men are sinners, cannot overcome this, and are therefore unworthy of Heaven. This is not to say that God doesn't give us the chance, but since Humans Are Flawed at best and Bastards at worst thanks to Original Sin, we're inevitably going to blow it. Thankfully, God was merciful enough to provide a way out: sending Jesus to Take The Heat on our behalf. Even so, He does want us at least try our best to keep His commandments, and to realize that He wants to save us. For this case, if you don't trust and have faith in Him like this - don't accept His authority, don't take His standards seriously, etc. - you're doomed.
Unsurprisingly, this structures much of the characters' journey in the 17th-century Christian allegory The Pilgrim's Progress.
It's especially chilling because it's such an out of character thing for her to say, but in an early Animorphs book, Rachel (correctly, as it turned out) identified the words "we have to win" as "the first four steps down the road to hell."
In The Adventurer by Mika Waltari, after the peasants' revolt led by Thomas Muntzer fails at Frankenhausen and as the leaders of the rebellion are being executed, a mercenary captain who is about to be executed looks at the bottom of his pint right after Muntzer has been beheaded and claims to see through it to hell where Thomas Muntzer is already along with a bunch of other people. Then he turns it upside down, pretending to look at heaven where he sees no one. (The naive narrator protagonist assures the reader that he probably didn't actually see hell or heaven through his pint.)
The Living End by Stanley Elkin is a darkly comedic novel based on this trope.
One The Far Side cartoon featured a scene in Hell with three rooms, one for terrorists, one for mass murderers, and one for "people who drove too slow in the fast lane". (Curiously, the guys in that third one didn't seem to be suffering as much as the ones in the other two.)
In Warhammer 40,000, everyone with a soul ends up in the Warp (this setting's version of Hell) after they die, no matter who they are or what their deeds in life were. Humans are lucky because their souls aren't powerful enough to remain conscious inside the Warp, but the default fate of Eldar take the cake. Their souls are extra tasty to Slaanesh, who will immediately consume any Eldar soul that finds itself in the Warp, so they have to carry soulstones with them at all times so that they don't go into the Warp when they die. And if they indulge too much in any emotion (especially pleasure), Slaanesh will swallow their souls before they die.
In Nobilis, the standards angels set for Heaven are very, very high. So much so, in fact, that not a single person has ever gotten into Heaven. Ever.
The Void, kind of, though it has more of an emphasis on "going to Heaven is hard". Ascending to a higher Limit is extraordinarily difficult and requires massive amounts of Color, while descending to a lower Limit is dangerously easy. Master Color even says, "All the easy routes only lead down."
College Roomies from Hell!!!: Satan plucks out Dave's soul, for no sin at all, essentially just to show he can. Some supernatural force saves him through Margaret and Roger, but that wasn't the author's original plan. And then there's this exchange:
Satan: Now let's say I put you in a situation where you have to kill someone to save [Margaret's] life. Then you die and go to Hell. And once you're there, your ass is mine... Dave: God would never allow that to happen! Satan: Sssss. That's what you think. The Other Guy doesn't care if you live or die. You're supposed to settle for eternal life.
In YU+ME: dream , Sister Mary routinely informs the students of things that will send them to hell. These include jumping on the bed, wearing striped socks to school, and running red lights.
Then again Sister Mary is all part of the Dream World of an angst filled teenager in a coma so she's rather overblown.
No matter how hard he tries to make up for his actions, Darwin Carmichael Is Going to Hell. Inverted, however, with a character who has so much good karma that she can get away with almost anything.
Sinfest isn't quite as extreme as some examples, but it's hard to say what Slick did to really deserve his various trips to Hell. (And then there are the people who fall into hellpits by not looking where they're going, or the guy who mistook the Devil for a T-shirt salesman and now burns while wearing a shirt that says "I made fun of the Devil" . . .)
A common urban legend about a paper made on Snopes site: whether hell is endothermic or exothermic states that hell must be really hot and getting worse because everyone has been cursed to go to hell by at least someone else in the world.
Bartleby Tales. The title character went to Hell for being gay, despite barely being pubescent and never having acted on his feelings.
In South Park: Bigger, Longer & Uncut, Kenny has been killed (again) and his soul drifts up towards heaven. However, as soon as he touches it, he gets an "Access Denied" message and tumbles straight down to Hell, which has a "Population" sign showing a huge and ever-increasing number, whilst the equivalent sign for Heaven revealed a tiny population. And it's not as if Kenny has exactly had time to sin much. All Played for Laughs of course.
Futurama: There's one robot church that has an easy condemnation to Robot Hell for robots. According to his agreement with his new church, all Bender has to do is sin once to be dragged off to Robot Hell. Ironically, they never mention robots who never joined that church going to Robot Hell, so Bender may have been better off if he had never converted.
Parodied and subverted by The Simpsons as Bart is on his way to Heaven on an escalator after being hit by a car, but gets sent to Hell for not holding onto the handrail and for spitting over the side (though Satan says it's more for his lifetime of evil deeds, and that the spitting over the side was the straw that broke the camel's back), then gets let back to Earth as the devil realizes it's not his time yet.
Parodied in Robot Chicken where a man meets Saint Peter who hands him a book that can answer any question about his life. He rapidly annoys the gatekeeper of heaven as he thinks it would be too boring to ask what he did right or wrong and instead asks how many times he heard I Touch Myself by The Divynils and how big a wall could be built using his entire life's supply of poo.
Satan: (impressed) 2.7 miles?!? Guy: I know, right?
Herculesindirectly implies this by merit of there only being one afterlife, like actual Greek mythology, but also pulling Everybody Hates Hades. The animated series explicitly shows the underworld is a G-rated hellnote When Athens technically becomes part of it, all the people are put into tailor-made eternal torments, albeit what we see is mostly Cool and Unusual Punishment. except the Elysian fields, which Hades isn't allowed to control and are only for heroes.